7-Zip, one of the most active and mature open source projects, has just reached version 9.20. Work on Version 9 only begun last year, in 2009, but it's already far ahead of the old version (4.65) in terms of speed and functionality.
If you've never used 7-Zip before, now's the time to start. In one fell swoop it removes any need for other compressed file managers. It's faster and slimmer than WinZip, and lacks the nag screens of WinRar -- and it supports more file formats to boot! After installing, 7-Zip (or '7z') sits innocuously in your right-click context menu, ready to decompress almost every archive under the sun.
With version 9.20, you can even decompress some EXE, FLV and SWF files, peek inside NTFS, FAT and VHD files, and the command-line tool has been beefed up considerably. There's also localizations for Hindi, Gujarati, Sanskrit, Tatar, Uyghur and Kazakh, meaning there's more than 70 supported languages.
Download 7-Zip for Windows, Mac and Linux