Since a fair number of people on these boards like to always post in a specific color/size/font face text, I think that the default BBCode hack would work well here. Basically, it lets users input a code so that every one of their posts will automatically begin with that default formatting--for example, you could set it so that all of your posts will be in dark blue and a slightly larger-size font, without you typing in any formatting tags when actually going to write up the post itself.

If you're interested, there's more information at the link up there, and as you can see, antialiasis (Dragonfree) made it, so I'm sure she could help you out if you needed it...