Sounds kinda silly, but I found a decent DM's screen really helps.
Goodman Games just released a 2-panel screen that has piles of useful combat move summaries (Grapple, Bull Rush, etc) as well as weapon & armor charts and brief summaries of most "normal" skill resolution rules inside the covers.
I applied a fixed Initiative (10 + Reflex) to the players and my monsters, and have the players sit in Initiative order. Speeds things up nicely.
I also go through the adventure ahead of time and, as Questing GM suggests, have an "options" list of things that can be done in battle. Obscure rule/feat/ability/spell? I jot down the page number in the PHB or DMG or MM that explains the info I need ahead of time, and can turn to it quickly during combat.
All these things have saved me a lot of time.
Also, I've stopped stressing out about adding every single buff and occasionally just plain fudging die rolls (to the party's favor or detriment, depending on the drama of the situation--this is a role-playing game, after all, so drama needs to take priority). Will it seem cooler for the players to win now? The NPC "rolled poorly". Does the fight need to last longer, or did I omit something? Ah, looks like the villain "rolled a natural 20," as I chuckle from behind the screen with a 4 on the d20.
Looks like some of the rules for Star Wars Saga edition could be handy, too--the natural 20 = critical hit with no confirm rule seems very fair.