There's an interesting new beta project from google launched today, which allows you to create custom search engines which focus on a given topic area by customising which sites are indexed as part of the search. I've created a couple of one's in areas that interest me .
I think that this could be really useful for targeted searches as it can cut out a lot of the "spam" and other less relevant sites from the search results.
This one is an Information Security Search engine. At the moment it's based on some sites which I use (list below), but if there are other ones that anyone would like to see include just leave a comment, or feel free to volunteer to help out on the search engine front page.
Anyway here's a link to the Information Security Search Engine Homepage
and here's an embedded version which google provide the code for