After seeing some interest in improving the trigger pull on AR's I rounded up a couple links that will help you drastically improve the factory Mil-spec trigger. I've done this on a number of AR's and the result is a very short clean and safe trigger pull. The changes are minimal and if for some reason you don't like it you can always put it right back with the purchase of a couple springs.
Here are the links. I perform both of these along with polishing the sear surfaces and will put it up against any single stage aftermarket trigger.
http://www.junkyardgenius.com/firearms/ar-15/ar08.html
http://www.sargenthome.com/15_Minute_AR_Trigger_Job.htm
The second link involves altering the trigger and hammer springs. The change to the hammer spring results in a much lighter hammer drop but as is stated in the link by the author, I have yet to encounter one single failure to ignite the primer. If you are worried about it I recommend that you simply try performing the modification on the first link and seeing what you think. The first link will greatly reduce take-up,creep and overtravel while the second will lighten the actual trigger pull. Now since the combination of both modifications both reduces spring tension on the hammer and trigger sear surfaces and reduces the amount of sear engagement it is VERY improtant that you insure that the safety is still operating properly and that the hammer won't drop when the safety is off due to a jolt. After it's all together I take the lower and with the safety selector in the "fire" position and, for lack of a better term, beat the living snot out of the thing to make sure the hammer won't fall on accident. Since you are just handling the lower seperate from the upper you aren't going to harm anything by slamming the butt stock on the floor etc.
One more note on the first link. When I put the set screw in I lightly screw it in until it wants to stop then cock the hammer back and slowly back the screw out until the disconnector releases the hammer and find this to be the "sweet spot". If you are worried about sear engagement you can continue backing the screw out until you are happy, this will increase the amount of sear engagement but wil also increase trigger creep.
Have fun.