I'm particularly interested in using ipfs pubsub capabilities. It looks like an interesting way of allowing multiple users of a web app to talk to each other without needing (much) server side support.
There's an old version (from June) of Orbit at http://orbit.libp2p.io which you can try. Much has happened since and we're working on bringing the js-ipfs version Orbit back to a working state.
Re.Pubsub, I'm personally also very excited about it! :) The specs and general info are located here https://github.com/libp2p/pubsub. go-ipfs merged pubsub into master some time ago with this commit https://github.com/ipfs/go-ipfs/commit/e1c40dfa347e38bdc9812... and we're working to get it into js-ipfs here https://github.com/ipfs/js-ipfs/issues/530.
IPFS and Matrix seem to be the only teams doing this: Dat and SSB have vague protocol documentation at best, only documenting bits of the protocol at all.