Fontfeed lists an impressive number of logos from Web 2.0 startups (or former startups)."A clear trend in new identities is the use of soft, rounded typefaces dominated by VAG Rounded, but also including Helvetica Rounded, Arial Rounded, Bryant, and FF Cocon. All of these lend a modern friendliness to the what might otherwise be a cold trademark."
If you were curious, Flickr uses Frutiger Black, last.fm uses ITC Ronda, while NewsGator uses ITC Bauhaus Medium.
