I work at home and I have a good friend who works in a corporate job. One or two times per month, she'll call me and ask me to keep her kids for the afternoon. I feel that she's started to see me as 'available' because I'm at home in the afternoons, even though I'm up to my eyeballs in work already. Any suggestions for how to extricate myself?

Advice here from WorldWit. A suggestion: put those kids to work brainstorming story ideas.