Just thought I'd share with other Mac users, OS 10 Yosemite breaks the foldit standalone client and the free 'student' version of MacPymol. (Note the foldit game client is fine.)
I tried the foldit standalone client for Mac on Yosemite and it doesn't work, it was fine on Mavericks. It installs and opens on Yosemite but when you try to load a valid PDB file it just fizzes out and closes.
http://www.macinchem.org/blog/files/0f5cfea643bdf4d2dfcae3991300b886-1611.php - also reports the student 1.3 version of MacPymol being broken.
Both of these apps were last updated in 2010.