Cryptic, makers of Champions Online, has introduced Archetype Rotation into the game from now through to the end of November. During the event, players are given an extra character slot and each week, a different archetype is spotlighted for players to try.
The schedule for the Archetype Rotation is as follows:
The links above lead to the Champions Online page for each archetype. Full information about the Archetype Rotation event are at this link.