Sometimes inspiration strikes inconveniently

Writers across the globe are scribbling furiously this month as they participate in NaNoWriMo. It's a fun adventure, and shows writers that regardless of your schedule or situation, you can make time to write about 2,000 words a day, and focus on a novel to get it done.

I'm not officially participating in NaNo this year, but I am working on the coffee house book. Focusing on one story is good. It lets me get into the characters and story. But, as can happen with writers, focusing on one story leads to a new, shiny idea begging to be written. It's happening to me right now, in fact. I have an idea for a story I think would be fun to write--much more fun than slogging through character biographies and background information for the coffee house book.

What do you do when this happens to you? Do you take a little time to jot ideas down? Do you use the shiny, new idea as a way to break from the WIP when you feel stuck? Do you ignore the new idea until you're ready to write it?