Oh, and now back to the original question:
Andrew, I'd write up your running resume, and then circulate it to whichever companies make products that you use and want discounted.
Another route (one I personally find more useful) would be to do the same with the local running stores, to see if they are interested in sponsoring you with free merchandise and possibly a small stipend for entry fees and travel expenses in exchange for sporting their logo. This has the advantage of not being tied down to one particular brand of shoe, drink, etc.
As someone mentioned above, Inov8 has a pretty decent program. Last I heard you received 10 pairs of shoes per year, a uniform (singlet, shorts, short sleeve, jacket, pants), and a backpack. They already sponsor some ultrarunners (like Brian Morrison, Mark Lundblad) and mountain runners (Joe Gray).
Nuun is very liberal with product; they'll give you tons of free product in exchange for sending them photos of yourself using their product/displaying their logo in races. However, this is kind of a joke because it seems that every ultrarunner has a Nuun "sponsorship", judging by the number of people wearing Nuun visors.
You might also want to try some online retailers, like Backcountry.com, who sponsors athletes like Matt Hart and Karl Meltzer.