I use The Unarchiver, which you can find for free in the App store, to unzip .zip and .rar (and other archive formats). OS X has a built in archiver that can create .zip files. I use SimplyRAR (also free, google it) to create .rar files.
Thanks so much for this thread and all the helpful information.
I was unarchiving RAR fonts in a really convoluted way --transferring them to a file in Virtual Box & Windows, unarchiving, then transferring again and to another account. I downloaded UnArchiver from the MAS and can't wait to try it out on the next RAR file.