As of yesterday, μRaiden (read: microRaiden), the scaled down version of the more popular project Raiden Network, has been deployed on the main Ethereum network.
The deployment consists of a set of smart contracts, which allows to open a many-to-one payment channel, which will act as an off-chain value exchange medium.
In layman terms, this could be used for a paywall protected website. The website is the "one" part in the contract, and the clients are the "many". So many clients could send small, free transactions to the same address, without using the blockchain.
Incidentally, this limited use case - many-to-one - is one of the particularities and differences of the μRaiden network, compared with Raiden Network, which allows for creation of arbitrary many-to-many payment channels.
In both protocols, though, once a channel is set up, there are no transaction fees anymore, as the identities of both the senders and receivers are confirmed and any payment will be just like moving tokens from one of your addresses to another one - there is no blockchain verification involved.
The release is a test one, and it comes with its own deployed token, RDN, which has a hard cap of 100 per channel. You can of course use your own ERC20 token, if you want, or ETH. The aim of the release is to be battle tested in real life.
If you want to know more about this release, including the contract address, you can read the GitHub announcement.
If you want to know more about μRaiden (I find the technolgy fascinating, by the way), have a look at the documentation.