I'm only surprised to not see any of Kenneth Reitz' work on this list, e.g. Requests. In fact in that vein is rauth, an OAuth client lib built on top of Requests (https://github.com/litl/rauth). Full disclosure: I'm the author of rauth. :)
> I specifically excluded awesome libs like requests, SQLAlchemy, Flask, fabric etc. because I think they're already pretty "main-stream". If you know what you're trying to do, it's almost guaranteed that you'll stumble over the aforementioned. This is a list of libraries that in my opinion should be better known, but aren't.