I was a bit sceptical about it, but we've been using egg-timers to good effect. In our group it's just used to limit the time it takes to actually decide what you're doing. Rolling the dice, determining effects, etc. comes afterwards. Coordinating efforts still works as long as players pay attention outside of their turns, e.g. the Barbarian player will say 'please leave this square free, so I can charge there' or the Rogue will ask 'can anyone move to flank with me?' Likewise the leader players decide who's going to help whom before it's their turn.
I think in our group it's also the controller player who takes the longest for his turn, followed by leader players. One reason for the controller player being slow is actually, that many of his powers have complicated effects and he simply doesn't know them very well. Being prepared and knowing your character's powers is very important to be able to decide on and resolve actions quickly.
What helps a lot is that we use a whiteboard to track initiative and any floating modifiers. We also use condition markers and cards.
I think in our group it's also the controller player who takes the longest for his turn, followed by leader players. One reason for the controller player being slow is actually, that many of his powers have complicated effects and he simply doesn't know them very well. Being prepared and knowing your character's powers is very important to be able to decide on and resolve actions quickly.
What helps a lot is that we use a whiteboard to track initiative and any floating modifiers. We also use condition markers and cards.