I went to the site expecting it to be an open-source library providing one convenient API into all the things you mention. In fact it wasn't until I went to the top menu looking for a Github or download link that I realized it was a hosted for-pay service. I think a library bringing all those things together (maybe without the geolocation part) would be useful, and I don't personally know of one.
Whoa! Super impressed you turned this out so quickly. You should post it as a 'Show HN' story!
Also, props for renaming it to session.js (I think it's unfair to use their name)
This might spur the visitor.js guys to release part of their codebase as open source and continue to provide a paid service with extra support and features etc.
