Disk Defragment and Disk Cleanup?

Defrag is not necessary for most users. OS X automatically defrags on the fly for filesizes under 20 MB. So unless you routinely work with large photo or video files, don't bother. Here is Apple's take on it.

As for a "CleanUp!" type app, OS X has automatic scripts that take of this sort of thing. But they do it in the middle of the night, and if your computer is off or sleeping, it might not do it as frequently as it should. OnyX and Maintenance (both available here) are good programs to help with manual cleanup. MainMenu is another good one.