Looks like a pretty happening barbeque party! I've had this one as my desktop background for so long now I can't even remember.

Pack Ice (pony at the bbq): (don't have a link for him :<)
Star (in the pool): Mine
Ellison (pink mare by the pool): http://askellisonpippin.tumblr.com/
Puddle (pony with the hose):
Fizzlebang (green, skeptical-looking pony):
City Sweep (giant face in the background): Mine

Art by http://askellisonpippin.tumblr.com/