Not sure if this has been suggested before:
A small tag or indicator by the poster's name if that posted is the one who started the thread - something like [op]
I think this was implemented on the mmorpg.com forums
The reason I suggest it is because I often don't look at the original poster's name, i suck at remembering names in general, and when browsing on page 2+ of a thread, I often wonder who original poster was. Yeah, having unique avatars, as many do, helps a lot, but not everyone's avatar is that memorable.
Funny you mention that, I'll often post my thoughts for users facing issues I've dealt with in the past. Unless i see certain avatars in the thread that is, (hodgman, here's looking at you) and then i just shut up and listen