User blog:Candycoateddoom/Before iCarly...

Miranda - played Summer Hathaway in School of Rock, and Megan Parker in Drake & Josh

Jennette - the one thing I remember her being in is an episode of Will & Grace called "Von Trapped", where she played Lisa.

Nathan - I remember him as a wheelchair-bound kid named Jamie in an episode of The Suite Life of Zack & Cody

Reed - also guest-starred on Will & Grace, as Will's flamboyant nephew, Jeordie

I'm sure there's more, I'll probably figure them out later.