I don't know how many times someone has asked me to look for an open source or Free Software app for them because they hate navigating SourceForge. (I LOVE navigating SourceForge, which is probably something I should use to build geek cred and not admit in public.)
Open Source Living is an index of the most popular and proven open source and Free Software applications around. Listings are for Windows, Macs and, of course, Linux and while not separated by OS, the listings are easy enough to get around in and understand. At least that's the mission statement. I note that the site carries a very Google-like beta tag. Still, it works fairly well and I urge you to have a look at it.