Try these:
http://www.filemanager.3ntar.net
and
http://www.binaryintellect.net/articles/44b73e89-78d9-4ad7-8157-bce54ad31fde.aspx
They are not that good but it's pretty straight forward to build one yourself. Just make a recursive function and populate a tree control.
I actually might have some code I wrote for one of the companies I worked for. Let me know if you are interested and I'll try to post it here somehow.
