There are various 2nd-tier search sites such as HotBot, iWon, Webcrawler and an enormous number of little known and little used search engines that pay a fee to one or other of the larger engines, or are the remaining rump of a once much bigger search engine that has fallen on hard times, and is being kept simply to exploit the brand loyalty that still exists.

Many are using the data from ODP under licence, or are using whatever technology their parent company has access to (for instance HotBot uses DirectHit, as does it parent at Lycos. It does use the Inktomi results as a filler however. Both use ODP data in their directory results). Trying to analyse them all is a mammoth task, and unless you are seeing significant traffic from them, probably not worth the effort.

There are also a few with some exposure among the webmaster community, mostly personal projects being run by one of a handful of visionaries looking to develop the next "big thing" in search technology, or simply to provide an alternative search destination.