Porn9.org

Actually, how to open rar, zip, bz2, gzip and almost all kind of compressed archives or even split avi/mpg files without joining them first...
Use 7zip, it's free and open source, doesn't require any cracks, serials or patches and can decompress dozens of formats and join any type of split files without the need to use another tool like HJ.
7-Zip works in Windows 7 / Vista / XP / 2008 / 2003 / 2000 / NT / ME / 98
http://7-zip.org/

So there you have it...
A better compression format and tool than winrar for compressing, decompressing or joining split files.
Let's hope uploaders start using 7zip more, instead of the old and outdated winrar...