One thing I've noticed that has been a slight annoyance is that the forum codes only seem to work in lower case letters. Would it be possible to make them work with uppercase? It's not a huge deal, but it's rather annoying typing out something, and then having to go back and lower the case (also, ImageShack gives you the preset codes in uppercase when you upload a picture).

I made the img tag work in uppercase as well for now, hopefully that'll work for you. It's still not truly case insensitive and that'll have to wait until I have more time.