Thanks for polling. I figured it'd be worthwhile to get some opinions before I started in on a decision, and this has achieved that.
I think I'll create a small-format calendar, perhaps just with a 5x7 image on top (let me know if larger is best). I'd like to find a way for them to be detachable, so after the month was over you'd be able to pass them along as a postcard-like gift that said "hey, ride a bike or keep doing it" to whomever you wished. Sold without profit to me, too.
It'll be a year end celebration, and will reflect a variety of riding--snow, transport, firetrails, among others. It won't happen until the end of December though, I'm cooking up graduate school applications and about to be back on the job hunt in force I'm afraid.