iBoostUp cleans out the crap on your drive and fine-tunes your system for better performance. It's simple, quick and free.
iBoostUp's interface is pretty straightforward. (You can see a quick look at the app in action in the video above.) You're initially brought to a status page that gives you a system overview plus a look at which scans you've run and when. You can click on any of the scans to run them, or access additional options via the sidebar on the left.
The Quick Scan option is what will interest most people, as it can save a good chunk of hard disk space in about a minute. It will clear browser cookies, however, which you may not want to delete. You can tell iBoostUp to leave the cookies (or anything else) alone if you want. Your other primary options include Disk Optimiser, which seems to be about the same as running a permissions repair in Disk Utility, and Network Optimiser, which will test your network response times and recommend how you can improve them (if possible).
Overall, the app just handles a few maintenance tasks, but it's a lot faster and simpler than tune-up behemoths like Onyx. If you want something a little less complicated that can speed and clean up your Mac in a minute or two, iBoostUp is worth a look.
iBoostUp (Free) [Mac App Store]