While being a useful tool for several years now, VLC has finally reached that first pinnacle of software development: 1.0.
VLC is an alternative media player for Mac, Windows and Linux that handles a wide variety of media file formats without requiring additional software (like Perian) to be installed on your system. It can also be used as a server to stream video on higher-bandwidth networks.
Personally, I think it's handy for things like making still frame images of DVDs, or capturing video from your EyeTV tuner. Anytime I have to send QuickTime or MP4 video to PC or Linux users, I recommend they download and install VLC to watch it.
The software isn't for everyone: If you're already familiar with VLC, the upgrade is a solid one. Performance is good, and the feature list is tough to beat. If you've never used VLC and you're happy with QuickTime Player (thank you very much), then feel free to pass this one by.
Binaries for VLC 1.0 are available for Intel-based Macs running Mac OS X Leopard (and developer previews of Snow Leopard). Source code and other, older packages for PowerPC and earlier versions of Mac OS X are also available.