I've been getting a lot of flat tires on my bike. (I counted five patches on my current front inner tube when I fixed it last night.) They're almost always from shards of glass that embed themselves in my tire. I think the bike lanes actually increase the frequency with which this happens: When car windows or bottles are broken, the glass that falls in car travel lanes is quickly pulverized and pushed aside by the traffic. In the bike lane, this takes a long time to happen, and the cars push the glass into the bike lane.
This is, of course, a huge pain. But I am taking decisive action. When I last got a back flat (a few weeks ago), I bought a puncture-resistant tire made with a tough rubber compound and woven kevlar in the tread. Now that I've gotten a front flat, I'm going to get one for that wheel, too. The brand is Specialized Armadillo, and according to this promotional video, I should be in good shape: