I have two pottery mugs from Marlborough Challenge that I love. I love the t-shirt from the 2012 Fling, took ages to arrive but is cannily shaped at the bottom so it doesn't float around. My favourite though is the Marmot down gillet I won as 2nd lady in the 2009 Beacons Ultra, have never won anything 'proper' before and I live in it!!
Other than that, medals are good if they are interesting - Shakespeare Marathon one is shaped like a book, and the fling ones are good, not quite sure what to do with my Centurion belt buckle for the SDW 100 - I like the theory but it's not the kind of buckle that is ever going to fit or I'm going to wear!!!
Tea and cake at the end of hill races win me over every time