Here's a question more people should ask, from the Good Agency blog: Pro bono. Where's the bono?
... it's not pro bono if there is no bono -- no actual good. No new donors, campaigners or volunteers. No new services funded or vulnerable people reached. No research paid for or hungry mouths fed.
Ad agencies and marketing companies like to do pro-bono work for nonprofits. It's a chance to bulk up their portfolios. (And who knows, maybe some of them just want to do good deeds.)
It turns out free work is worth about what it costs you: nothing.
If someone does a really cool project that makes you say ooh but lays an egg in the donor marketplace, you've taken a bigger hit than you might think...
The most common and uncounted cost is opportunity cost -- hours spent managing a dealing with a pro bono project that could have been spent doing something productive.
Then there's damage that can be done to your brand by heedless work that's driven by creative whim.
Just take a run through this shop of horrors and you'll see how badly things can go awry. And that free doesn't necessarily mean good. Or even free.