You'd think everyone would use Markdown or some variation of it by now. Well, everyone does except Slashdot. And I still frequent a web forum designed in 1999, and it supports forum markup.
I wonder if they never changed because they think their system is better, or they just don't want to devote the resources. Or perhaps they like it worse as a natural barrier-to-entry to posting to keep out fifthly casuals and their signal-to-noise ratio. But I think that's giving them too much credit.
Next up in Slashdot Beta, all posts use a flash applet running in a java runtime that emulates VIM!