Providing consumer opinions about products can be one of the most directly useful applications of a community-built data bank. ProductWiki ( www.productwiki.com/ ) is an attempt to collect such information, using a bloglike format. It’s not quite there as a resource site yet, but as a heads-up about keen products, it’s pretty good. Where else would you learn about a USB– controlled launcher ( www.productwiki.com/usb_missile_launcher/ ) that aims and fires foam missiles using keyboard commands?