Hi Matt
I know of a few around Mt Tamborine (Cedar Creek and another one close to one of the main intersections up there - Curtis Falls). I have also been to other creeks around Brisbane such as Cedar Creek (yeah - same name but this one is to the north of Brisbane) north of Samford where I have taken some flowing water shots but these aren't big falls.
I also remember there is a part of Mt Cootha called Slaughter Falls - could be a chance of some water falls there
I would also think there would be some up around Mt Glorious / Mt Nebo way.
If you want a slightly longer drive then there are a few up around Maleny and Mapleton (Kondalilla rings a bell).