In tournament stage, allow 4 (or 8) competitors in same match, with half advancing.
A great feature would be an option to adjust how many players/teams are in each match, with half advancing from the match. For example, a standard match has 2 teams, with half advancing (one). If we allowed for 4 teams/competitors in a match (two advancing), this allows for challonge to be more friendly to tournaments where games have a preference to four players/teams. Think games like Age of Empires 2, where you have 4 or 8 players in a match, with half advancing to the next round. Or couch multiplayer games such as Fuzion Frenzy (4 players always in a match).
Obviously the finals match must determine a 1,2,3 and 4, but prior to that, its always two advancing.
I've run many tournaments like this, and it's perhaps my biggest desire for Challonge to incorporate this feature.
A potential "problem" that comes with this is that, conceivably, two competitors could play each other in every match in the tournament (if they were paired up in round 1 and take top 2 in every match). A possible solution would be a reseed after every stage. I myself never reseeded, and I've never had two competitors play in more than three matches together.