I'm generally a firm believer in only worrying about Google and Yahoo for marketing and SEO purposes. I won't mess with submitting to the 56,214 smaller ones and I certainly won't pay anyone else to do so. But, a reader sent me this page that lists a number of interesting, smaller search engines. I'm having fun with God Checker right now. One of my offspring is named after a Norse god, so I'm finding it interesting.
There is also PicSearch, which could end up being pretty valuable when trying to find specific copyright-free pictures, or when you're wasting time looking at crap online. Fellow freelance writers might also be interested in the Writer's Web search engine for quick information.
Some of these smaller, more specialized search engines can be good for finding specialized information quickly, but I'm not sure that they are much good for marketing. I may end up using a few of them, but I don't think that time spent submitting to them would be spent well. The vast majority still search using Google and Yahoo. Interestingly, more people apparently use Yahoo than Google. I don't know anyone who uses Yahoo, but apparently millions of people do. Who are these Yahoo people?