In the three most recent offices I've needed to nap in, I napped: Sitting on a sofa with my head back against the wall; lying down on an oversized bean-bag cushion; in a computer chair, with my butt moved towards the front of it and my head back against the top of the back (the back wasn't tall enough unless I scootched forward). The last was obviously the least comfortable.

In general, I've found the biggest obstacles are social (i.e., people think you're lazy), not logistical. But these are largely gone for me now that I'm running my own company. My cofounder and I have vowed to not just tell any future employees that napping is acceptable, but to actually keep doing it, so they see that we're serious and feel comfortable napping themselves should they want to.

I'd recommend telling your coworkers/boss that napping makes you more productive, and that you only take one 20-minute nap a day. If they're silly and care about exact minutes worked, just show up a few minutes early or start a bit later.