Crossroads.js seems to be one of the best around. One major advantage of it being, it doesn't rely on window.location for routing. It's lightweight as it sticks to do just routing and routing alone.
Others you may want to try: finch.js,
davisjs (based on pushState so that you can use existing links as a fallback if JS fails)
Appending an update: March 30 2015 -
I had moved to AngularJS late last year. Hands-down the best switch form JQ, has a lot of modules like routing in-built.
