Meta-search engine is a web-based service that aggregates data from a number of search engines. A meta search engine doesn't have a database of indexed pages of its own. Instead it "sends a user's query to multiple search engines and blends the top results from each into one overall list."

Some helpful features meta-search engines offer are:
Besides, some newly launched meta-search tools offer a few really creative and innovative approaches: combining regular search engines and social media sites (e.g. FuzzFind) or outlining the results on a map showing the links between different search engines (Langreiter.com) , etc.
However, most (if not all) meta-search tools are no better than an individual search engine as neither of them seemed to develop an effective blending technology and relevancy leaves much to be desired:
| Search engines | Main feature | More options | Advanced search abilities |
Relevance (my take) |
Other search types | |
| Clusty | Ask.com, Gigablast, Live, NY Times, ODP, Shopzilla, Yahoo news, Yahoo stocks | Term clusters | TLD stats | Boolean operators (OR, -, +), filetype and language restricted search | Low, too many "sponsored results" | News, images, logs, shops |
| DogPile | Google, Yahoo, Ask, Live | Search suggestions (related terms); recent searches | - | Boolean operators ("", -) | High | Images, audio, video, news, Yellow Pages, White Pages |
| IxQuick | All the Web, Exalead, Qkport, Ask, Gigablast, Wikipedia, Bebo, MSN, Winzy, CNN, NBC, Yahoo, EntireWeb, OPD |
"Star" system (the more stars = the more search engines agree on the listing rankings). | Multiple language support | Boolean operators (OR, -, +) | High | Video, images |
| IBoogie | AllTheWeb, MSN | Term clusters | "Add your source" option | - | Low | Images, news |
| Kartoo | N/A | Search results on a map | Term clustering | - | Low | Images, video |
| SurfWax | CNN, Yahoo news, HotBot, ODP, Yahoo news, MSN, AllTheWeb | Snapping = displaying the summary of the page containing the search query | - | No | Moderate | - |
| Mamma | Ask.com, About.com, Entireweb, Business.com, Gigablast, Wisenut, ODP | Add/ Exclude any of the search engines | "Refine your query" search suggestions | Boolean operators ("", -, +), | Moderate | Video, Yellow Pages, White Pages |
| Search | Google, Ask.com, MSN, ODP | - | "Narrow/ Expand Your Search" search suggestions | Boolean operators (OR, -, +, ""), filetype, language, update time, linkdomain restricted search | Moderate | Images, video, people, shopping, music, news, games |
| Meta Crawler | Google, Yahoo, MSN, Ask | - | Preferences: Bold search on/off, recent searches on/off | Boolean operators (OR, -, +, "") | Moderate, too many "sponsored results" | Images, audio, video, news, Yellow Pages, White Pages |
| Fuzz Find | Google, Yahoo and MSN and from Del.icio.us | Sort the results based on any of the sources | - | No | High | No |
So does meta-search have any future? Well, it does. In today's web 2.0 (and emerging web 3.0) Internet there are plenty of promising ways for meta-search to evolve:
Ann Smarty is a search engine and social media consultant blogging at Search Engine Journal and offering SEO consulting services.
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