TinyUrl is awesome for shortening long links but it’s annoying that you don’t know what you’re clicking on sometimes.
Normally I look at the bottom line of my browser (Officially known as the Status Bar in Firefox) before clicking on a link to see what I’m about to get. Often it’s something descriptive like http://www.ibm.com/some/such/marketing/crap which I know that I don’t need to click on. But if it’s just http://tinyurl.com/3dbfym then I have to guess, which can be annoying.
I’m not worried about being goatse’d at work, though some people might be.
It’s good for things where you have to copy and paste a link (like in some documents) or have limited space (like twitter) but it’s usually unnecessary on a regular old web page. Please make sure you provide context so I know what I’m about to click on.