Well, not many places anyways. Anyways, even if they did allow it, most likely an admin and mod would have to do it for you, there is no system which allows you to do it.
Now, if there is, don't tell me. I'm simply voicing my opinion.
Heres my opinion on the issue.I really don't see why it would be so confusing if it showed your username,although seriously I think the nickname could be out under the username is smaller text.I do see a use for this in case someone is in a club or something within the site,and your are not changing your username.I really don't see why it couldn't be done,and think that some others just don't always see the big picture with some of these ideas.Also I see no point in implementing the AP system into this,unless you want to make it an extra feature for more active members or something.The only con of this would probably be the unlikely chance that no one ends up using it and it wasting shpigford's time,or that it somehow lags up the database server.Still I don't get how it could be confusing,when their name never changes,but just their nickname,which I think would be best not to make larger,or more noticeable then the real/original username.Thats all I can really think of on the matter as of right now.
Maybe just being able to change it once. if you chnge it much more it would get confusing. it should still show your user name, with your nick name under it.
Maybe change it twice every year maximum? And so...on all your comments and forum posts, your nickname would be showed but your real username is only on your profile?
maybe..hmm lets see,spending ap is one way but too many people cried and whined about my idea..and i guess noone noticed my "If you get a certain amount of ap you could change or keep your username,nicknames..cant we just call eachother that? if you want to call be by nickname im draven