Here’s a list of some cool (and basically free, I think) apps for the Mac. I have some of them, but there are some others here worth checking out.
Also, there’s this fine advice on the Mac Observer for backing up your Mac. Actually, this advice is pretty much appropriate for any computer, and really, since PCs are more vulnerable to various viruses and such than Macs, advice on the need to back up is probably more important for PC owners.
I have to say it is not quite the new “the dog ate my homework,” but “my computer has a virus” or something like that is close to does surface as an excuse once in a while. Maybe I need to create some sort of student guide to computer maintenance…. or somebody does….