Awhile back I posted a link to Google's Pack website. While it did a good job of offering great free programs, it did sneak in a few stinkers (real player and Norton), Lifehack has taken it upon themselves to offer the best in free software in a simple list. While its not in a single download like Google's, it still does a good job. Here are a few that I would recomend.
Open Office: Ever feel like a few hundred on the newest Microsoft Office suite was too much? Well, run to pick up this program fast then. Compatible with microsoft file formats, you can't beat its price at $0.00
Ad Aware: If you haven't installed an anti-spyware program yet, install this now.
The full list can be found at Lifehacker's site