I just spotted a new RSS search engine called RSS Micro. It seems that they're still adding features, but the result set isn't too bad. However, there's one problem here that I've seen a lot recently - ajax and permalinks. Since RSS Micro is using ajax, the search is extremely fast. However, this also means that there's no way for me to link to a search results page (I can't, for instance, link to the results page for "mashable"). If you're going to use ajax for page loads, you need to seriously consider your permalink structure - at the very least, offer a permalink for each search page, even if it doesn't appear in the address bar. I had a similar problem with the filtering process on Jobby - I can subscribe to any filter via RSS, but there doesn't seem to be a permalink for the page itself.