Pure Mac: Mac Software Listing

Pure Mac has a great listing of many mac software, not only for OS X but for earlier version of Mac. Not all listed softwares are free, but they will tell you exactly what is the license of every software. This site got updated frequently, but unfortunately there is no RSS feed to check for the latest Mac Software on this site.

FreeMacware: Free mac software blog

Freemacware.com is a good source to find free mac software. It gets updated almost daily, and it contains many free (gratis and/or open source) software. This site may not show you the best new free software for Mac, but it will show you the most useful one.