Every "Web 2.0" site dreads being too successful, and for Webkinz, that unhappy situation arrived December 26. Webkinz, if you're not familiar with them, are furry stuffed animals that have a Web 2.0 social media site that accompanies them. My kids are crazy for Webkinz, rifling all the local stores (and the San Jose Tech Museum) for them.Every Webkinz comes with a numbered tag. You enter the tag number at the Webkinz site and "adopt" your pet. By playing games, you earn KinzCash, with which you can buy stuff for your pet. There is a social media element to the site, in that you can interact with other people signed in by choosing from a number of available statements (e.g., "How are you today" and the like); limiting the interaction to Webkinz-provided statements precludes unacceptable language and the like. You can learn more about Webkinz at wikipedia.Wikepedia's entry on the little furry beasties seems to imply that Webkinz has passed its popularity peak, but, based on December 26, I'm not so sure. That's when my sons, eager to register their new pets, found the Webkinz site down. I think the site pooped out under the load of a zillion kids all wanting to get up and running with their new pet.I asked one of my sons to walk me through Webkinz world. It seems like you complete various tasks to earn money to decorate your pet's house and keep it fed, happy, and healthy. Frankly, it all seemed a bit too much like work for me to generate much enthusiasm for it. However, for kids of a certain age, Webkinz is catnip.During the tour, one of the pages faulted and displayed an SQL error. I didn't get a chance to look at it in detail, but from a cursory look it sure seemed like a MySQL error. It certainly makes sense Webkinz world is open source-based. Open source powers most of the highly-scaled Web 2.0 offerings, since their businesses need significant scalability without increased software license fees every time they need to add new servers to keep up with the usage.Overall, I'd say Webkinz is a particularly brilliant offering. By tying participation to a physical good, the company can fund the technology without having to rely on ads, which many parents (myself included) find unacceptable. Certainly the company extracts a premium price for the animals, giving it better margins in a (forgive me) dog-eat-dog toy market. And using open source (assuming they do, which is a pretty safe bet) means their social site, which offers a more engaging experience than a mere stuffed animal, is affordable to build at scale.Another site my son has gotten involved with is scratch. A business colleague told me about and my son has really gotten into it. It's a programming environment for children and is so intriguing that it deserves its own posting, which I'll try and write soon.