On Byfeed.com you can get a short unique ID for your feed. It works with RSS 0.90, 0.91, 0.92, 0.93, 0.94, 1.0, 2.0 and Atom feeds. Short numbers instead of long paths, open service for all feed-aggregators and online feed-catalogs. What do you think about this project?
Well ppl will probably like to go by feedburner route. Most of the shorts are taken there but still... too much of a hassle. Tinyurl is popular for some totally other reasons which don't apply for feeds.