BestCollegesOnline.com has put out quite a good list of 50 Awesome Search Engines Every Librarian Should Know About. The list is divided into the following sections:
* Meta Search and Multi Search Engines
* Multimedia and Interactive
* Google Search Engines
* Custom Searches
* Reference Searches
* Library Search Engines
While many of the search engines are well known, and some have been covered in Learning 2.0 and 2.1, this is still a good list. And while you are checking out the BestCollegesOnline.com blog, check out the other entry: 50 Firefox 3 Add-ons That Will Change the Way You Surf the Web.