Paid two bucks a gallon for gas the other day . . . first time. And while I know many of you have suffered this indignity for a while, the experience tested my stoicism about the ebb and flow of prices at the pump.It also made all the more satisfying my first trip to www.gasbuddy.com, a site that has seen traffic skyrocket from 30,000 to a half-million daily visitors since January, according to co-founder Jason Toewes.A nonprofit outfit that boasts 174 affiliated Web sites, Gasbuddy uses a roster of 110,000 volunteers to keep motorists abreast of the best gas deals available where they live, no matter how miserable those deals may be these days. The spotters report price information about the stations they pass in their travels, with some actually going out of their way to gather prices much as bird watchers seek rarities. The resultant database lets visitors see at a glance which stations near them are charging the least and most, a spread that can reach 20% within a few blocks, according to Gasbuddy. (A similar commercial site, www.gaspricewatch.com, does much the same thing.)The gas-price watchers are prime examples of a growing Web site trend that enlists armies of like-minded volunteers to collect information about this or that and present the results online for amusement, social good and perhaps a shot at business profit.The New York Times recently profiled an oddball example - www.payphone-project.com - that pairs up the physical locations and numbers of a half-million pay phones, information the telephone companies refuse to make public and the public apparently finds useful in ways both trivial and dramatic. Another I stumbled across last week - the National Incident Notification Network - enlists owners of police and fire scanners to scoop the press by reporting car accidents, plane crashes and other neighborhood carnage to www.ninn.org the moment it crackles across emergency channels.The gas sites are clearly more practical, of course, especially given the current run-up in prices.On my visit, Gasbuddy had prices for several of the stations I frequent. One had the highest prices in my region, while the other had the second-lowest. Guess which one is more likely to get my future business?Utility aside, it seems to me that volunteer-dependent sites of this nature are ripe for producing erroneous data, both of the accidental and fraudulent varieties. However, Toewes insists that Gasbuddy has mechanisms in place for flagging both and doesn't hesitate to ban shady operators from posting prices.Yes, I understand that gas prices today are not historically high when adjusted for inflation, but they're plenty high enough to annoy. So why pay more when another station down the street is charging less and all it takes to find the bargain is a mouse click or two?Heck, yes, I'm glad to be backPeople mean well, of course, but the question - "Are you glad to be back?" - started to strike me as amusing after about the fourth or fifth instance.A month and a half ago, a surgeon cracked open my chest and yanked an egg-sized tumor off my heart. The tumor turned out to be benign, but coming as this did on top of my December heart attack . . . well, you might understand why being anywhere other than a hospital bed would be cause for obvious joy.But before we settle back into our weekly conversation about more mundane matters, I'd like to thank my colleagues Adam Gaffin and Melissa Shaw for so ably filling this space in my absence. And many thanks, as well, to those of you who sent messages of support.The address hasn't changed: email@example.com.