I experimented with this a lot, and have asked a lot of elite level athletes and coaches (one being an anonymous NCAA 1500m champ, another being Joe Vigil) and countless other coaches of all levels and abilities.
a few observations i've had over the years:
-it seems to me that strides have become a showcasing of finishing kick abilities at many track/ xc meets. most inexperienced (and sometimes good) runners sprint really hard for 60-100m and do this several times before the race, in both directions, not really knowing what they're doing. it's been clear that in most cases, the coach said, "do strides as part of your warm-up."
-some strides are as long as 150m and as short as 50m, and are at varying intensities. If one does not know the why/ how in doing them, the application is a waste.
-strides post run are different than pre-race or workout warm-up situations.
my applications:
1. strides after an easy run are a great idea, as they activate fast-twitch muscle fibers. preferably done flat, barefoot on grass, and possibly including a push-up/ sit-up routine can be an enjoyable way to finish the run.
the more mature I got in my racing career, and something that I had my athletes do once per week, was to do the strides in the middle of an easy run. So if they did an out and back 60 minute run, at 30ish minutes at a park, they'd do the strides there. usually barefoot on flat grass at goal 800m pace--quick, but not all out. this would be 8-12x 80-100m, and recovery would be standing, until the athlete isn't breathing heavy. if done on a football field, recovery would be a jog across the end zone; we called these boxes, and would complete 1 set of 5.
2. uphill strides are excellent at building hip strength and mobility. as long as they are not done at a high intensity level, and the hill is gradual, they can be beneficial. depending on the intensity/ hill/ surface (grass, asphalt, dirt), you may want to adjust the recovery. downhill strides can be effective, so long as you're not crashing hard on your way down.
3. warm-up and pre-race strides should always be done the same way. the race and workout warm-up routines should be the exact same every time (now, a 1500m warm-up may differ from that of 10k XC, so keep that in mind. one race is 4 minutes long, the other is 30 minutes). nevertheless, i believe that the warm-up should mostly be active, and in between the low intensity jogging and high intensity strides, a transitional intensity activity such as drills should be done. this is especially important for both the heart, and the muscle fibers, as the transition will go from zero intensity (resting on the bus ride to the race) to high intensity a minute into the race.
4. Strides should be like a story: beginning, middle and end. The beginning, you go from a stationary/ low movement phase, and progress into a higher faster running during the 2nd phase, and finally, come in for your landing, as you coast towards the end. If one is doing 100m strides, break it up by 30m build-up (the first 5-10m may even be more like a bound, as your starting from a standing position), and hit your top speed (which in most cases is not very fast (800/1500m races are different) and hold it for 40m, and coast back down the final 30m. this same concept can be applied to shorter or longer strides, and the intensities can be adjusted as well.
a few final closing thoughts:
I once watched Chris Lukezic do 4 strides after an easy run the day before an important 1500m race. This was when he was competing for Reebok in 2007. He ran 4x150 with full recovery, running each 50m faster than the previous. I was told once by one of his competitors (I'd like to keep him anonymous since he's not here to say it), "I'm only afraid of Lukezic's kick. He can launch into it within about 2-3 steps from 200m out. Webb takes 5-6 steps and lacks the explosiveness needed to get into his kick. As long as i'm a few steps ahead of Lukezic with 200m to go, i'll beat him every time." So Lukezic's 4x150m strides were definitely playing to his strengths.
I hope this helps answer your question. for future research, try Jay Johnson's videos, they are excellent. Especially his aerobic work warm-up.
http://vimeo.com/coachjayjohnson/videos/page:5/sort:date