There are some pretty decent ideas about 'wounds' and the like rumbling around in the 4e House rules forum. They make the game more lethal, but if that is what you are looking for then that might be the way to go.
But as some people have mentioned, the danger of 4e is really when you can't just have 1 fight, blow all your dailies and an action point and then rest up for the next fight. PCs will be able to handle encounters way way above their level if you do this. The danger really comes in when it becomes difficult/impossible to take a liesurely rest whenever you like. Time pressure, harsh enviroment or hostile surroundings that make resting out of the question until the adventurers resolve the situation they are in its entireity. If you are going to be having 3 or more encounters in a row in a day you need to be careful about tampering with healing surges. When they run out, you HAVE to stop and rest or you will die. Have you checked out the 'updated' monster stats? Monster damage is higher now. Maybe that added deadliness will make your players thankful that they recover after an extended rest. If your having one encounter and then rest, then tamper away!
As for speeding things up. That won't likely happen until everyone masters their characters and the rules. But you can give incentives to people to encounrage them to stay focused and take their turn fast. One of the best ideas I've seen on these boards was the following:
If players finish their turn in under a minute they receive a token. That token can be cashed in at any time to add a plus one bonus to any roll. If you use two at once it gives a plus two. I think 3 could be traded in for a 'Drama Card'. (I downloaded a whole bunch of pretty darn neat 'Drama Cards' on an entry I found on wikipedia.) Anyway, I can't remember exactly the system the person whose idea this was used, but you see where I'm going. Besides, turning that roll that missed by 1 into a hit ... well that in itself is going to help speed combat as well.
At my table we have all agreed to the use of a timer, with timekeeper and all. The time keeper advises when the first minute of a turn is up. When the 2 minute mark is reached the turn is over. If you use an action point you get another minute. Actions that have been announced can be resolved before the turn passes on.
I give Versatile Expertise to my players as a free feat. This makes them more accurate, which means they hit a lot. Which means they kill things faster. (Plus they don't have to waste a feat slot on something so important, but so flavourless)
Also, my mosters rarely fight to the death, and certainly never 'just because'. When a fight has been won but monsters are still standing I end it in a way that makes sense depending on the situation. And I'm careful not to unfairly punish them for letting these monsters flee or surrender (not all the time of course ... and sometimes they implode, collapse, explode or disappear altogether). Another option, when you decide the battle has been lost but it has to be fought to the death, is to turn all the monsters still standing into minions: the next hit kills them.
I also like to build non-combat solutions into my combat encounters. Yes, these headless skeletons that clawed their way out of the ground on the edge of the cemetary will mindlessly claw you to bits until you smash them to dust, unless you return their severed heads that are dangling from the branches of that cursed and defiled tree in the middle of the cemetary. But that of course will be a challenge in itself.
Another house rule floating around on these boards which I have introduced with great success into my own game is the : Do Something Cool Power Card.
This is basically an encounter power whereby the player can have their character do something particularly cool that makes sense in the given situation. I allow the players to use this in conjunction with powers they have, but altering or adding special effects that make sense. I guess it goes without saying that any repetitive abuse of the card or a particular tactic means it is no longer cool and hence no longer works. This is not guaranteed to speed up combat but it will add a pretty damn fun element to it, and give your players the explicit permission to step out of the box with their characters and what they try to pull off.
Good Luck!
