I hurt my hamstring last year when I went sprinting without warming up properly (most likely cause anyway – might have been other factors too; whatever). I was limping for a couple of days, lost range of motion and could barely walk let alone run.
First big shock: it takes ages to heal. I'm 8 months down the road, and I have just resumed outside sprinting (I did treadmill work only since June, with one brief period outside that caused a regression). It's still not fully healed either, as it reminds me it's there every now and then. I don't know if this will always be the case (as I fear), or whether, with time, it will become fully healed without any "reminders of existence" (I wouldn't call it pain, an occasional discomfort – usually when I sit down for a while).
One thing that has helped me enormously is a new stretching routine for the lower body. I got it from a couple of really good strength conditioning coaches (Mike Roberstson and Eric Cressy) – they have a DVD called Magnificent Mobility. It ain't cheap at $50, but I swear it's helped me a lot. The focus is on lower body flexibility. I used to do a load of static stretches and even some "ballistic" stretches (didn't really know what I was doing, and obviously didn't learn from articles…I had to see them on a screen before I finally worked out how to do it "more properly").
I also do Epsom salts bath after a hard leg-workout (GH raises and all that) and/or sprinting. No idea if it helps, but it's easy to do. 🙂 Touch-wood, things have gone well for me – I am able to resume outside sprints 1-2 times/week with no problems, which I'm very happy about. 🙂