Interesting topic. I have some figures to make: An Uruk-Hai, Legolas, Freddy Kruger (Nightmare), Conner MacLeod (Highlander), Spiderman, Darth Vader and a Star Wars Stormtrooper.
So I guess I just have to pick a few for this Groupbuild.
I plan to make a 1/35 Blackhawk Down Dio with a Blackhawk, two Littlebirds, a Technical, some buildings and lots of figures, but I it would take me more tha a year to finish it so I guess it won't fit for a GB.
Have you thought about start and end dates?