This is a 1500 pt. list I'm thinking of putting together for Astronomi-con next year. I assembled this list using the army composition rules on the astronomi-con site and JWolfs ACL article from back in June.
HQ
Terminator Librarian w/ Vortex and Smite
Elite
Terminator Squad x5 w/ 4 Chain Fists and Assault Cannon
Troops
Tactical Marines x10 w/ Missile Launcher, Melta Gun, PF
Razorback (TLHB)
Tactical Marines x10 w/ Missile Launcher, Melta Gun, PF
Razorback (TLHB)
Tactical Marines x10 w/ Multi Melta, Flamer, PF
Drop Pod w/ Locator Beacon
Fast
Land Speeder Squad x2 w/ 2 Heavy Bolters and 2 Multi Meltas
Heavy Support
Devastator Squad x10 w/ 2 Multi Meltas and 2 Missile Launchers
Rhino
3 - 6 Objective Takers and 11 KP.
I think this list has a competent array of answers to pretty much everything that can come at it. Use a Gun Line w/ speed bump combat squads to vs. assaulty Armies. Against shooty forces, i can drop Deep Strikers and use transports as cover.
Any glaring holes I've missed?