The ZigZag team has released an alpha version of their crypto asset exchange that works on the Lightning Network, creating one of the early testable examples of the Lightning Network and showing potential to decrease fees in payment channels.

* Note that in their roadmap, at this first phase they are still serving as a trusted exchange (not trustless):
"In this phase the exchange of funds shall require the user to trust us to pass these funds onto the target/destination address."

* However, their stated intention is to develop payment channels that incorporate atomic swaps, and they intend to incentivize participation in payment channels by allowing external investors to earn money by locking their funds in a payment channel.

""You can now trade your testnet Lightning coins for testnet altcoins! Check out using @Bitlumio to swap your https://t.co/cOYGcwWbbP freebie testnet coins onto a testnet @BitGo web wallet. https://t.co/OC1EIrw3xA

 — @alexbosworth""

Promising news. Still approach proceed with caution that you would apply to another exchange until they get to atomic swaps.

Source: https://medium.com/bitlum/zigzag-alpha-release-12b7c56e53b2