Another thing we could try once we get going is have a theme say every 3rd month.
Bit like what you would have in a show'n'shine
Eg. Best exterior (kits,wheels), best interior (seats, console, lights, sound/entertainment), best engine bay (layout, color scheme), best auto :P, best tracked car (track pics only!), etc...
And during State of Origin QLD and NSW members can pick 1 representative from each state and let the two duel it out Or even a team of cars of 3-5 (team with most points win :D)
but yeah.. just some ideas to make it bit a more interesting, and hopefully inspire and motivate members to keep modding :P