OSX Cool App: The Unarchiver
This is one utility that will make your whole archive experience more pleasant. With support for almost every archive format known to man, and the ability to rejoin split .rar files as well as natively unzip .Jar files its all the rage on the scene atm.
Best of all you can set it to by default show the files that its just unachieved in the finder, alleviating that whole, wheres that stinking file that i just unzipped.
So my advice, get this cool utility, it will make your day!