RAR files is common package and compression format that is used by people who share files in rapidshare. As one of rapidshare fan, I always found the shared files are in RAR format. So, if you are Ubuntu Gutsy user like me, you may notice that unrar (the program to open RAR files) is not installed by default.
No Problem... you can simply install it in less than a minute. Open up your Terminal (Application > Accessories > Terminal ) and issue this command:
$ sudo apt-get install unrar
Then after it is installed, you can now right click on the file and click on Extract Here. Isn't it simple?