Who knew that the Hanson brothers would be such Web frontiersman? First the wholesome threesome hooked up with Internet impresario David Bowie and Ultrastar to create a state-of-the-art web presence. Now they're taking another step into the unknown with a 3-D chat and concert on May 6. What do we mean by that? When fans go to www.worlds.com, they will be asked to create an "avatar," essentially a paper-doll rendering of themselves, from a virtual ID kit. Fans can either approximate what they actually look like, or go wild and become a six-foot-tall amazon with blonde dreads. Then the super-fan creations will be able to chat with Zac, Taylor or Ike -- or other fans who log in for the cyber event -- or "experience the concert as if it were live," or so the wigs at Worlds.com tell us. . .