The benefits don't stop on the hiring side. I would gladly do this for any position it looks like I'm qualified for, for two reasons. One is that it gives at least some idea what the work is like. The other is that I've discovered I turn into an idiot when asked to code in an interview setting while someone else is watching. :P

(Shameless plug: I am looking, if anyone is after a decent Python programmer. Email in profile.)