Cursebird is a realtime feed of people swearing on Twitter. Fuck, yeah!
I don't think the end of Catcher In The Rye will have quite the same impact after browsing through the signs on display here. This is big and it is clever.
I saw Steven Pinker give a talk recently and he spent a fair amount of time talking about swearing. He has written up that part of the talk into an article for the New Republic.