Well, personally, I had a couple of ideas for contests-
-What would the TOS bridge look like if it was designed/built today
-Different federation warp nacelle designs over different eras (For those of us with engineering backgrounds that LOVE power
)
-Support craft (shuttles, supply ships, tankers)
-orbital starbases
EDIT: one more - I'd like to see people's renderings of what they think Spock saw when he looked in his scanner in TOS.