When I wrote my free and open source post a few days ago, I left out one really nice application that I use alot: 7-zip. 7-zip is a free file compression archiver that can zip your files into a number of formats including ZIP, TAR, GZIP, and their own format 7z. The 7z format is self-extracting so, for instance, if you needed to compress a large file to email someone, they would not need a special app to unpack the file after receiving it. If you are running windows like me, the install wizard automatically puts an action link in your right-click menu so using 7-zip on any file requires just 2 clicks. Awesome. You can download it here.