Google Scholar

Cool, Google cloned CiteSeer with Google Scholar. When I was in school, CiteSeer (aka ResearchIndex) was an invaluable tool for finding scientific articles. I'm sure that with Google's increased indexing power and agreements with publishers, Google Scholar will become even more vital.

Compare results for "fast multiresolution image query":

Google Scholar

CiteSeer

(CiteSeer is a little slow, I think because of all the people checking it out compared to Scholar ;)