It appears I have actually been living in a cave, because the oddly successful Join Me campaign passed me by entirely in 2002 (and onwards). And also, I did read Are You Dave Gorman before this. That book was pointless, yet life-affirming - and it had something important to say about friendship, and being nice to people. Nothing you could quite pin down, though.
Danny Wallace's first solo book, detailing his quest to get 1000 people to "Join him", is hilarious. Like Are You Dave Gorman, it's occasionally a little convenient and hard-to-believe at best. But life imitates art, and strange things really do happen.
Also, unlike said novel, Join Me has a definite message, and Danny's collective isn't a "bored man's experiment" at all. It merely started as one. It's basically a religion, minus all the trappings of sermons and scripture, with just a single aim: make people happy by being nice to them. It's starkly simple stuff, and the sense throughout the novel that Danny truly doesn't see the scale of what he's done is rather humbling. Hundreds join him out of sheer curiosity and trust. Hundreds do good deeds, finally feeling they have the excuse and right to. After reading this, you'll be truly hard-pressed not to sign up.
If anything, the book makes the human race seem a warmer, more lovable breed than before. An absolutely touching, sweet (and more importantly), funny story.