Just want to share an idea that crossed my mind.
The moods in msn messenger change according to the emoticons you use.
Would it be nice to see something like this for standard forums? I think it's a quite unique idea to let a bot check the smileys you use in posts, and adapt your mood-rate likewise, and then change your avatar picture which is located at the same server.
Or maybe just an extension to mybboard for example, but I don't have much experience with that.
Anyway, it would probably waste way too much traffic
/ 
Forum moods
