A virtual convention could be held using a virtual world, for example Second Life. IBM did this successfully at the end of 2008 and it is gaining momentum as a means of holding meetings, conventions and seminars.
Pros
Potentially far more delegates could attend.
Delegates could attend for only the sessions they want.
The cost would be much less for delegates than a attending a physical convention.
It would reduce carbon emissions.
Wikidot might be the first wikifarm to hold a convention in this way which would be good publicity.
Cons
Setup and design will be quite complex.
Delegates would have to sign up for Second Life and download the client. Some training sessions in advance would be useful as well as a "dry run" and some means of giving help and assistance at the event itself.
Users would need minimum computer specs including headphone and microphone (or headset).
Background Documents
IBM Case Stud pdf: second_life_case_study_ibm.pdf