http://raiden.network/ - This is a promising project leveraging off-chain state networks. Are there any early adopters for this technology ? I couldn't find any examples or sample applications on their github page.
Raiden hasn't shipped yet so there are no projects using it in production. IIUC Gnosis has been experimenting with it, among others.
We're working on state channels for our games (at Better Gaming). we've got it working, in prototype form. We're not using Raiden because they don't yet support arbitrary state and don't have a timeline on when it works.