I'd like to compile a list. Perhaps to transfer over to the wiki eventually. Even though many browsers still do not support @font-face AND many foundries won't allow it, I think it would be useful. And I hate to get complicated, but can you copy/paste the information from the foundries EULA which states the accord?
I'll start:
Foundry: exljbris
Quote: You may use this font for Font-Face embedding, but only if you put a link to www.exljbris.nl on your page and/or put this notice /* A font by Jos Buivenga (exljbris) -> www.exljbris.nl */ in your CSS file as near as possible to the piece of code that declares the Font-Face embedding of this font.