Towels.

Books Yesterday would have been Douglas Adams's sixty-first birthday and to mark the occasion, Google's home page doodle was a rather nifty tribute with working guide and cameo from the television Marvin. Now their blog's been update with a permanent copy and words from one of the designers:

"The world (to be fair, the universe) of The Hitchhiker's Guide to the Galaxy is complex, chaotic, and often contradictory, with multiple timelines and probability axes colliding in assuredly comic ways. The various exotic planets, alien races, and intergalactic sociopolitical situations are usually filtered through the lens of the series' most useful piece of futuristic technology – the Guide itself, published out of Ursa Minor Beta. The Guide's task of organizing the galaxy's information struck a chord with us, which is why we gave it special attention in our doodle. Through it, you can get a small peek into the unrelentingly hilarious universe created by Douglas Adams."

... and it's a sodding tragedy that Douglas didn't live to see what amounts to his Guide appear in (just about) everyone's pockets.