My attendance at The Cantab has been more sporadic, and I find myself not keeping track of the prompts as well as I should be. I've been looking through notebooks, doc files, all over the place to see if I've recorded the prompts somewhere, but a couple of them appear to be lost forever.
But I found other things.
So, go through your notebooks, if you're one of those analog people, your word processing files, your texts, and find a scrap of something you wrote that you intended to be longer.
Don't bother trying to remember what Previous You was going to do with that scrap, take it and make something entirely new.
Write Or Die
Scott Woods's Twitter Prompts
Rachel Mckibbens' Prompt Blog
The 30/30 Prompt Blog
Asterisk And Sidebar Prompts