My main sources for this are newsgroups, and friends who send me random things via email. I'll also give pointers to other peoples' (or groups') things, and recomendations of offline things. Where possible, I acknowlege the author/source of something, but as often happens with the net, attributions get lost.
Working with computers for a living has attuned me to stuff which you might not find funny.
I will freely admit to being an anti-Microsoft bigot, and to liking both Macintosh and Unix. I'll also admit that Microsoft occasionally gets things right, and that Apple can (and often does) get things wrong, and that Unix will not solve all the world's problems. These views probably affect what I find funny. If you disagree, then fine. Just don't complain to me - I didn't force you to read any of this.
Anything marked (dated) is probably extremely topical. For example, many Windows 95 jokes depended on the fact that it seemed perpetually late. Others simply allude to "forthcoming" software.