I've considered, on a number of occasions, putting some sort of 'plug' or 'advert' into my O-Wheely! mod...
e.g. During BG Preparation a message into local chat something like
[FRED] just buffed you all using O-Wheely! - buffing made easy at
http://www.wowinterface.com/blahblah...
It would obviously need to be kept to an ABSOLUTE minimum - but I'm sort-of worried people will be annoyed by it regardless and so I've never done it.
It's a VERY obvious way to promote your addons tho - what do you lot think - good idea or bad?