CleanMyMac has been a powerful tool for Mac maintenance for a long time. CleanMyMac 2 has just arrived, and it is even more powerful than previous versions.
The app now has an auto-cleanup function that looks for non-needed files and cleans them up, not by simply deleting them, perish the thought, but by asking you first. The app also removes old logs and caches, and can take a significant whack at your iPhoto library by deleting master copies of previously edited photos. CleanMyMac 2 has also applied a fresh and more direct GUI making some of the more complex operations simpler.
The app can also uninstall apps no longer being used, and hunt for unused extensions and control panels. I have used the original for quite some time, and I expected the latest version to have an upgrade cost. Nope. It's free for current users. The company also provides a trial version which allows you to remove up to 500 MB of stuff for free.