I just ran across sleepinginairports.net, thanks to the MIMlist listserv. Calling it the "budget travelers guide to sleeping in airports," the site offers reviews of various airports' sleepability, plus a bunch of other silly stuff. I have to agree that London's Heathrow is a great place to catch some zzz's--as someone who can't sleep on a plane, I've napped there many a time on layovers on the way to elsewhere in Europe. Here's one hidden gem of a Heathrow napatorium, according to one of the site's readers:
I work as a ski rep occasionally, and my return journey from the Austrian Alps inevitably involves a 6 hour wait at Heathrow Terminal 2 to travel back to my home town of Edinburgh, Scotland. I have therefore identified the perfect bench and regularly get a good 4 and a half hours sleep, during the day! Once into terminal 2, go down the big wide corridor to gate 5. A little further on, there are some very comfortable curvy, cushioned benches, about seven feet long and with no arms! Perfect! The airport staff don't care if you sleep there, and it is very quiet. I know that long sleeps are not normally required by the domestic airline passenger in the UK, but when you've been on a debauched week of skiing and drinking, sleep is your biggest craving!"
The airport sleeping tips also are pretty cute, such as arrivals areas usually have more comfortable seating than departures areas, and tips on what you should carry in your emergency airport napping kit, including a "cheap inflatable pool raft (they fold up nicely and make the hard floor a lot more comfortable). However, keep in mind that in some airports sleeping on the floor is a no-no."