Fiasco has many advantages for the busy gamer. It's highly structured and runs as a one-shot game of about 2-3 hours length. It's focused on a series of one-to-one scenes which the other players watch and adjudicate on, which makes it just about perfect for Skype or Hangout play. There are online dice rollers and simultaneous file sharing software to run the index cards and all-important dice. It requires about four players overall and as there is no chronicle does not require a fixed group.
ETA: Oh yes, and most of the playsets are free, making it a doddle for everyone to get a copy even if playing over Skype.
The more I think of it, the more perfect it seems.
So, now I just need to pitch it to you guys:
Fiasco was designed to accommodate collaborative storytelling in the milieu of modern noir; the world of the Cohen Brothers and Elmore Leonard, where greed and lust and the occasional good intention collide in a catastrophe of post-hubristic downfall, and while later playsets have widened the field a little, it still holds to the same basic structure.
Set-up - Roll a bunch of dice and use those with the playset's tables to determine the relationships between your characters and the needs, objects and locations they will interact with. Once those are established, decide who you're actually playing.
Act 1 - Take it in turns to play out scenes which develop the themes you've selected.
Tilt - Set up a change halfway through.
Act 2 - As Act 1, but with a focus on moving to your resolution.
Epilogue - A final montage for your characters.
The dice not only set the options for plot elements, but also provide a pacing mechanism. Each scene gives someone a die. When you're halfway through, you tilt; when you're out, it's done and you narrate your epilogue based on the dice you've collected. It's not exactly roleplaying the way we're used to it, but it looks like a lot of fun.
Need more explanation/convincing? Here's Table Top doing Fiasco: