Teoma, which means "expert" in Gaelic, is a major search engine you may have never heard of, that is because it was only launched in April of 2001. Also, the reason it is considered a major search engine, is that since it was bought by AskJeeves.com in Sept of 2001 it has powered Ask.com, which is still a fairly popular search portal.
Teoma was launched in post-Google world and so their ranking algorithm is very similar to Google's, as is the case with most search engines now. To get ranked highly on Teoma you need in context incoming links, and a good keyword density on your site. However Teoma does do some things different. For one it still takes the meta keywords tag into account, however only slightly. Additionally Teoma segregates its results into two sections. There are "Results" which are your typical search results like you'd find at Google, and then over to the left there are "Resources" which are much different. Whereas typical Google-like algorithms are used to garner the main "Results" listings, the "Resources" listings are compiled using a complete different algorithm. In the "Resource" section you'll find hub sites, that is sites that are mostly just links to authority sites. So to generate the rankings for that section Teoma looks at outgoing, instead of incoming links. Currently they are the only engine to do this.
Teoma does not currently have a free submission option, though if you have incoming links to your site you will likely get listed for free eventually. Their paid submission costs a minimum of $30.
Teoma is definitely a search engine to watch. Their results are relevant and their "Refine" suggestions and "Resources" results are two features that not every engine offers.