I have variables stored in json that the client needs to read but I don't want the user to have to download them all due to the huge file size. Is there a nodejs framework that makes it relatively easy for client and server to share variables?
There's this module called Now which seems to do what you want.
Meteor is a stack that takes full advantage of websockets, making the client/server realm a continuum.
It uses JSON RPC, and does not rely on huge REST collections - this approach has pros and cons, but it's up to you investigate further.