Good Resources on Operating/Administering MongoDB
The best resource has to be the MongoDB docs themselves ...

http://www.mongodb.org/display/DOCS/Home

I'm constantly finding something new there.

Secondly, I'd say you should run the "try MongoDB" in browser tutorial available here, it's awesome. You can try out querying and everything without installing anything.

http://try.mongodb.org/

Also, I'd personally recommend very highly these two tools:


MongoVUE (Windows MongoDB GUI)
RockMongo (PHP MongoDB interface, beats the pants off the others.)


You can also see my stackoverflow answer here for more details on MongoDB gui's also there are lots of videos available here: http://www.10gen.com/video

Lastly, you can check out http://learnmongo.com for a lot of beginners resources (full disclosure, I founded the site.)