How do I make a HTML tree for a set of nodes?

Hi, I have a set of nodes. Each node has a parent and so the set can be thought of as a tree. I want to show that tree somehow on a webpage, served by PHP. I cannot use Dot/Graphwiz for various reasons. What I'm looking for is an output of DIVs or tablecells, showing the nodes and their connections. It's not a trivial task, IMO, but doable. Possibly somebody has already made something similiar, but I can't find anything on Google. Can anybody point me to helpful information? Thanks, Niels