Among the thriving herd of young professionals moving downtown or nearby, it's inevitable that there eventually would be children among them. (Even the best birth control is, after all, less than perfect.) This leaves an obvious vacuum regarding what to do with the kids on a weekend afternoon. Driving out of downtown to entertain them seems to defeat the purpose of moving back there in the first place, and while the winos at the central library are often entertaining, they're not exactly rated G. Instead, take the wee urbanites to America's Ice Garden at Plaza of the Americas. This ice center offers public skating and private lessons and can help you set up ice skating parties for the kids' next birthdays. They also have a pro shop to help you with your skating needs. With a little preparation now, your little one could blossom into the next Tara Lipinski or Rudy Galindo.