It's clearly not what you're asking for; but if you are starting a URL Shortener, you may want this one for SEO purposes:
Shortener{dot}net
The .com version isn't approachable with offers under $5000; and who knows what his final asking price would be. My BIN price is $2500. And I believe this domain is worth it for anybody who can scrape together the money. It nearly sold over the weekend to an existing URL shortener, and it may sell any day. It's a crowded and competitive niche. Even GoDaddy and Google are involved with URL shorteners of their own.