Dave, as I wrote you via PM you have my vote too to run the contest(s)
About the rules, I seconded wallyweb's
proposal.
I think the proposed maximum of eight entries for each month should be sufficient atm. If more is required due to popularity in the future this could be raised up and a solution have to be found how to poll it then.
There should also be a minimum of entries for a valid contest, I think. Imho it doesn't make sense to run a contest only with one or two entries. I'd say at least three entries are required. If there is a month with less entries it would just be skipped.
As robotboy already suggested the may contest should be skipped so we could use the rest of the month to 'design' the new thing
Michael has also made a very valid point about comparing pure pixel art with rendered stuff. Those shouldn't be mixed in one contest, because it would be unfair in some kind. Michael has explained very well imho.
The monthly contests shouldn't have any kind of topic so artists are totally free. Maybe we could run topic-related contest once in a year (in december) with several categories like 'best train set', 'best industry set', ... of the year.
That's all I can think of atm.
Regards
Sleepie