I was saddened to learn the other day that Sheldon Brown, a human encyclopedia of bicycle knowledge, died on the 3rd of February from a heart attack. If you've never heard of Sheldon, go to the treasure trove of knowledge that is his website. He'd been sick for a while, so I don't know how unexpected this was, but it's still kinda a shock.
Anytime a friend asks me a question about fixing bikes in a situation where I'm not there (over the phone or email), and I want to avoid spending an hour writing the answer down, or drawing a diagram or making lists of tools, I send them over to his site. In fact, I learned a great deal myself from his site when I was just a wee little bike mechanic, and still visit the site pretty regularly for technical specifications or just to check out his impressive compilation of weird bicycles. Sheldon will be sorely missed by the international following of bicycle enthusiasts that he inspired.