Meet the NeoPet, an addictive Web phenomenon spreading among children from Atlanta to Argentina. NeoPets require frequent attention from their owners, who must feed the critters, educate them, and keep them out of harm’s way.

Raising a NeoPet is a popular project. The 2-year-old, free site, originally created by British college students, has climbed to the top of game site rankings in recent months–with people spending more time on the site than at major competitors such as America Online.