As what the title indicates: what is a good program for doing some system cleanup, in order to save some space in the drive (kind of like the disc cleanup available for Windows 7)? Thanks.
Generally speaking, you'll save more space by removing user files than by removing anything else. There isn't a lot of "fluff" in a Mac OS X installation, so it doesn't need cleanup like some Windows installations. I've had good success using Monolingual to remove unwanted languages and architectures. It saved over 2GB. However, you need to be very careful in what you select to remove. Always backup your drive before doing any space-saving clean up. One app that I would not recommend, based on the number of complaints that have been posted in this forum and elsewhere, is CleanMyMac. As an example: CleanMyMac cleaned too much
OmniDiskSweeper Free, fast and powerful Gives you directory size right from the top level to any drill-down.