A major frustration for me is the seeming lack of information regarding which typefaces in a given library are technically suited to rendering small type across all browser platforms. I've basically been surfing these websites in IE6 with cleartype disabled (painful!) to get an idea of the worst-case-scenario for each typeface.
I love the fact that WebType groups their offerings by intended display size, and I was very impressed with the performance of BentonSansRE. At Typotheque, I was impressed with Fedra Sans Screen. At FontDeck, I noticed that most of their own site text is crisply rendered in PT Sans, which ironically enough is available for free.
Does anyone have tips on how to streamline this research/testing/font-selection process? Has somebody already done this work for me and published the results somewhere? I'd love to specify some fresh web type on an upcoming project, but at this point Verdana is looking pretty convenient.