The real answer is ... No.
So far as I have found there is no reasonable or publicly available Windows MonogoDB client which is really very sad since MongoDB is pretty sweet.
I've thought about throwing together a simple app with WPF on Codeplex ... but I haven't been super motivated.
What would features would you be interested in having? Maybe you can inspire me or others?
For example, do you just want to view DBs / collections & perhaps simple edits (so you don't have to use the shell) or do you require something more complex?