Note: you might want to read How Do You Roleplay Without a GM? first, in order to understand what our goal is here.
Having cut up the perfect GM into pieces, and assigned some of the most important pieces – creating the adventure, and the world it’s set in – to procedural systems, we’re now going to distribute the rest of the pieces to the players.
Some of the GM’s usual functions will be covered by all the players in common: see Special Powers for Players. Yes, players, not characters.
Some of the GM’s other functions will be covered by specific players, individually. This can happen informally – in many groups, people will just start taking up the slack whenever necessary, and there will be no need to create formal arrangements. But if your group need a bit of help with this – or if you just want to have a think about what kind of slack needs to be picked up – you might want to use something like these Distributed GM Role Cards.
The Collaborative Gamer 