I'm not quite sure why metasearch engines aren't more popular than they are. They are actually pretty darn useful much of the time, but they languish far down the list of popular search engines. Still, I don't think it hurts to take a fresh look at them now and then, so today's post is all about the metasearch engine.
First, let's make sure everyone is clear on what a metasearch engine is. It is not a search engine that ranks sites based on meta tags. It is a search engine that grabs results from a multitude of search engines (and/or directories), and returns those results, usually mixed together using its own algorithm. I'm not sure if returning results for each search engine separately (such as in different tabs) would really qualify as a metasearch engine or not, but I'm going to include that kind here as well.
I've listed them in alphabetical order because most of them would end up ranking about the same - somewhere in the middle of the pack - and I wouldn't know which to put ahead of the others. It should be obvious by my comments, however, which I like the best, and which I think are just so-so. In addition, I'm sure there are more that could have been included, and there are certainly lots of vertical search engines that might qualify as a meta engine too, but I couldn't list every possibility here. If you are searching for a meta engine, one of these will probably work well for you.
Clicking the condensed search results image for each one will open the full-sized image in a separate window or tab
Clusty - From Clusty's "about" page: "Clusty queries several top search engines, combines the results, and generates an ordered list based on comparative ranking." and "But what really makes Clusty unique is what happens after you search. Instead of delivering millions of search results in one long list, our search engine groups similar results together into clusters." As you can see from the screenshots, each result includes a listing of the search engines used to grab that result. So the #1 site lists Live, Open Directory, Ask, and Gigablast. Then, on the left side, you see all the different clusters that you can use to further refine your query. Clicking a cluster will change the results listed and may bring up sub-clusters to choose from. I'm not sure if Clusty (or its parent Vivisimo) was the first to cluster or not, but it was certainly one of the forerunners of this style of presentation, and is definitely useful.
Dogpile - It seems like Dogpile has been around forever. Just the fact that they still exist must count for something, despite its less than savory name. From Dogpile's "about" page: "Dogpile puts the power all the leading search engines together in one search box to deliver the best combined results. The process is more efficient and yields more relevant results." Basically, Dogpile is the very definition of metasearch, in that it grabs results from Google, Yahoo, Live, and Ask, and then sorts them based on their own algo. You can see they also list which search engines each result was pulled from, with each result showing a listing such as [Found on Google, Yahoo! Search, Ask.com].
Excite - Another oldie, Excite has been around for quite a while. It's home page is now portal-like, but once you search, you get the standard look and feel of a search engine results page. From Excite's "learn more" page: "We gather results from the top engines in the business, and compile them to give you the best possible results for your search. It's a pretty simple equation, and it means you get all the top results from the leading search engines on the Web." So again, standard metasearch, presented in the typical fashion, with the standard list of search engines next to each result. Everything about Excite just seems too busy and old-school for me.
Hotbot - This oldster gets some low marks from me. You start by choosing to search either Ask, MSN, or lyGo (whatever that is). Then, as you can see from the screenshot, the entire above-the-fold screen area is nothing but sponsored results. Yep, everything you see in that screenshot there is sponsored. All the organic results are below that. That's enough right there for me to walk away from it forever. What you don't see, at the bottom, are just the standard results from whichever engine you chose. Yawn.
Info - Info.com is a metasearch engine that uses both standard search engines such as Google, Yahoo, Live, and Ask, as well as directories such as DMOZ and pay-per-click directories to pull its results from. Info presents the organic results on the left side and the sponsored results on the right, with each using up 1/2 of the screen real estate. Info also has several tabs for specialized results from shopping engines, travel, reference, etc., all powered by other sites with whom they've partnered.
Ixquick - IxQuick is a metasearch engine that claims to have more accurate results because (from their "about" page), "An Ixquick result is awarded one star for every search engine that chooses it as one of the ten best results for your search. So a five star result means that five search engines agreed on the result." Sounds to me like a pretty standard way of returning results from various engines, but maybe its more advanced than I give it credit for. In any case, the output is what you'd expect from a standard metasearch engine.
Kartoo - Kartoo has the most unique output of this bunch, as is obvious. Kartoo is highly graphical, presenting results as a "map". Hovering over any of the results then gives more info about that result in the upper left corner, overlaying the Topics list. On the map, the results are "ranked" visually, by showing page icons in a smaller or larger size. The larger the page icon, the more relevant the result. Although this visual style wouldn't be my preference, it earns itself some credit for being different.
Mamma - Mamma's been around for ages as well. It's "about" page has tons of information about metasearch engines in general, and the ranking algo that Mamma uses specifically. "The search engines Mamma.com queries often return duplicate results. Instead of simply eliminating the duplicates as many metasearch engines may do, we use this information to rank our results. Each duplicate search result is considered a 'vote' for that result. Pages with the highest number of votes go at the top of our result set." Again, it sounds like a standard way of ranking results from various search engines. And, as you can see, the output is fairly typical. Ho-hum.
Metacrawler - Using Infospace's engine, Metacrawler plays around with weighting between commercial and non-commercial results, depending upon what it determines is the "intent" of the user's search query. Regardless of which it weights more, both will be included in a result set, but one will be more heavily favored over another. The output is the familiar one we've come to expect by now, and is nothing to shout about.
Myriad - Myriad Search was created by one of our own, Aaron Wall, and puts more of the weighting power into your own hands. You can choose to have it place more weight on some engines than others, which is interesting if you feel that one engine provides higher quality results than another. It then presents the output in several tabs, with the "All" tab being the "mixed" version, and then each engine having its own tab as well. I'm not crazy about having to scroll down to get to the results, but other than that, the combination of ratings control, mixed output, and individual engine results tabs make for a nice change of pace.
Sproose - I covered Sproose in more detail recently, but basically it's a metasearch engine combined with a social network. Once the algo returns the blended results, users can then vote up the results they like best. There are lots of pros and cons with user-improved search results, but if nothing else, Sproose stands out from the pack with its unique social features.
Zuula - Zuula is a metasearch engine that falls into the non-blended style, in which each engine's results are presented separately as tabs. However, Zuula has some features that make it more interesting in that you can choose which tabs to display, and in what order. For SEOs in particular, the non-blended results makes life easier when comparing search engine results. For that reason, and also because the output is fresh, clean, and easy to read, Zuula gets the "My Favorite" vote, and is the one I'd use over all the others.
Note: Each of these engines may have various settings, preferences, and features available that I didn't list.