another one that i think members find useful is the avatar (or personal icon) mod.
its a great way to make the boards a little more personal.
instead of really being identified by the screen name, users get used to seeing 'homer simpson' or 'batman' or ... well... me! i find that it adds a lot of personality to each post, as you get a better feel of what a person is like by the icon they chose (similar to a signature line or image)
things you have to keep in mind:
graphics need to load. so, if you're going to add the avatar mod, do your best to be in full control of what pictures can or can not be used. on my site, i created all the avatars, with the idea that they all had to be at, or under, 1k, to help minimize page load time (especially in an instance where there are 15 or so different members posting on one thread -- thats 15 extra images to load up, and if each were 'just' 3 or 4k, that could add an extra full minute to download time for an AOL user).
