[jQuery] json-to-tree?

Hi All,
Anyone know of a tree plugin that can populate from a json source (with
minimal fuss)?
How about a breadcrumbing plugin that can read from a json source?
I basically have a bunch of nested categories in json and am exploring
various navigation options, focusing mainly on plugins that won't
require much reconstruction of the json data, ideally able to read from
a json source (locally or remotely, doesn't matter...I can fetch the
remote as needed).
I looked at some Ext 2.0 tree demo's that can do it, but am looking for
a jquery way.
TIA,
Jack