In addition to the obvious - transportation, fitness, fun, maybe even green-ness - bicycles and the bicycling lifestyle also provide a benefit that, in my opinion, doesn't get enough attention: liberation from dependency on political and economic factors.
Here in Minnesota, we just experienced a prolonged state government shutdown, which was resolved with a divisive political deal that seems likely to produce an even more severe budget problem in a year or two. The federal government is now apparently facing the possibility of an unprecedented default on its debts, and few of us can guess where that will lead, even if it doesn't happen. Many of our customers and friends have experienced layoffs and career transitions that resulted in personal financial challenges. Gas prices have bounced around, and now seem to be holding steady well north of $3/gallon. Through it all, people who ride bikes have continued to enjoy riding bikes. During a grocery run on my Surly Cross-Check fixed-gear a couple weeks ago, I was fortunate to observe this sunset while riding my bike.
Once you have a decent bike or two (or six), riding the bike is pretty much free, regardless of how much money you make, and regardless of the state of public affairs. Sure, tires and other parts wear out over time, but it's probably true for most of us that a typical month's worth of gasoline and car maintenance will cost more than a typical year's worth of bike repairs, if we're smart about it.
I was musing over breakfast this morning that I have not been a regular driver in more that seven years now! I have the HC shop truck, but it has been idle for at least 2 months. I doubt it has more than 100 miles on it for all of 2011. I find driving and keeping up with the expenses that go with it to be generally stressful, but riding my bike, even in suboptimal weather, is generally a good time. I expect that this will continue to be the case, even if the proverbial shit continues to hit the proverbial fan.