I can't think of any programs that do that. Mac users are generally a trustworthy group . If the people you are dealing with are not very smart, just check in the Apple menu under "Recent Items...", it will show any recent applications and documents that were opened. Just clear the menu before the next person uses the computer, and you can increase the number of items remembered in System Preferences>Appearance (General). If you are concerned about security, make a new user account and let other people use that. That way, they cannot access your files.
i'm pretty sure there are logs of all sorts of different stuff somewhere in OS X. just try a search in the Finder... should turn up something.
sounds like you're after some out there app, probably most likely not mainstream... i've seen a few keystroke loggers at some Mac 'hacking' sites, but i've never touched them. Mac users usually are a trustworthy group, but after all it is a hacking site...
i'm sure if there is an app to record keystrokes, there would be something for tracking other stuff. good luck, and let us know if you turn up any useful apps.