Here are some things that drive me kind of crazy on websites:

• When the hover state of a text link changes the font weight, it looks bad and can mess with the layout
• When body copy is composed of images of text. It is just plain bad. Spiders can’t read it, site readers can read it, it is tedious to update. I am a font junky as much as the next person but is having everything in Mrs.Eaves instead of Georgia that horrible?
• Three column layouts almost never look good.
• Having to still design some sites at 770px wide, if someone doesn’t have a better graphics card/monitor, too bad for them. Same for hacking sites for IE6. *Angrily shakes fist at IE*
• All the coding support forums that have excellent content but ugly layouts.
• Flash sites with excessive loading times and non-intuitive UI.

That is all… for now.