I've been working with node since v0.2.x
Mostly JSON API's. I wrote an oauth library awhile back from spec to talk to the tumblr api. Recently I've been moving away from node for API's and towards Clojure, but that's a different issue.
As for Mongo, I've set up sharded, replicated deployments for clients to run node API's off of. Typically on AWS. I've also worked with GridFS for image/metadata storage and retrieval.
I was hesitant to put it so high because I am not intimately familiar with the gritty plumbing of Mongo, which lends strength to your point that skill bars are pretty subjective.
In the end, I made the skill bars as a way of saying "I'm competent to work with these technologies" and as a comparison between the various tech I have listed.
You are correct though. A frame of reference is important. I do plan to place aside information either in popovers or attached sidebars.
edit: That's an interesting comment about the education space. I placed it highly because I actually dropped out of college to start my own consulting business. In that way it would not represent the traditional model of a Harvard education representing the top of the chain and would add more to the story of how I became who I am, and how I can drive a company forward.
edit2: Thank you for making me look at the Education section again. I now understand why you think I'm still in school, awaiting a degree. Changing the wording now.