LogoInstant is a service which provide free downloads of logos in professional-style (Web 2.0). you can download along with source file with which logo was designed (for example, the file formatin Photoshop with all its features, such as levels or layers of layers, which allow a more flexible edition of the different components of the graph.)
The logos includes categories like most downloaded,most rated, making it possible to see which ones have been chosen more often. For that, in addition, there is the category of “Time” and the “Best Value”. It’s absolutely free, while accepting voluntary donations.
I say “totally” because you can use them for personal and commercial projects without conditions.
Link: Logo Instant