For some time now, I've been reading The Daily WTF, a weblog that exists to make fun of bad programming. Now, I've seen plenty of bad programming in my time, I've even written some, but the things that show up here are generally quite unbelievable. Usually they involve someone reinventing a completely bog-standard mechanism, like loops or pointers and trying to re-implement it without realising that there is a one-line way of doing what they are after.
Here's an instance that almost anyone can see is a bad idea:
This was supposed to be one of the things that integration hubs would get rid of. If everyone can export XML, and everyone can read XML, then all you need is a hub in the middle making sure that the XML gets to the right place. For some reason, it never seems to work out that well in practice though.
(Via The Daily WTF.)