RarMachine is a powerful RAR archive manager that you can use it to compress and extract all RAR files downloaded on internet or compressed on a PC.
WinRAR is one of the most powerful and useful archiving tools on the net so a tool like this is long overdue. RarMachine can compress any type of file and extract RAR archives with ease. There's no need to access Terminal as the whole archiving process is automated. This makes is much easier to use than RAR which has no GUI at all.
It is also fully integrated with Finder and it also allows you to use a password, create divisions in RAR files and extract divided RAR files. Everything you need to perform with RarMachine can be accessed by Ctrl-clicking or right-clicking and accessing it through the 'More' menu. Probably the only real downsides are that RarMachine doesn't compress batches of files and it's not free, although it's very cheap to upgrade.
For anyone that's been struggling to open, compress and manage RAR files on their Mac, RarMachine will be a breathe of fresh air.