I confess I am not much enamoured of Google design, what with that choice of startling blue and all, but they have taken a great step in the direction of redemption:
The Google Font Directory lets you browse all the fonts available via the Google Font API. All fonts in the directory are available for use on your website under an open source license and served by Google servers.
If ever you have suffered the [non] choice between Verdana and Arial, shuddered at the inability to rely on at least Helvetica, then this is emancipatory news. How does this magic work. See CSS:@font-face.
[Link: Google Font Directory]