Yes: Rootstock ( https://www.rsk.co/ ). This exists as a sidechain to the bitcoin network and implements the Ethereum virtual machine. It launched on mainnet yesterday.

Keep in mind that rootstock currently is a federated sidechain, so it is decentralized only insofar as you consider federated cryptocurrency systems to be "decentralized" (and different folks disagree about this)

s/mainnet/testnet/ according to https://media.rsk.co/announcement-upcoming-rsk-testnet-reset...

No, it's currently running on mainnet: https://media.rsk.co/getting-started-with-bamboo-rsk-mainnet...

eos.io just released alpha ahead of schedule https://steemit.com/eos/@eosio/eos-io-dawn-2-0-released-and-...

Quite a few:

https://www.reddit.com/r/ethtrader/comments/6b64if/list_of_e...

If Tezos ever arrives it might be a viable alternative for certain use cases.

Look at Tezos Github commits: https://github.com/tezos/

Most of them are shallow changes or "busy work" to show activity. I have been watching FileCoin and Tezos Github, and I wouldn't expect much from either one of them.

NEO, Stratas, NXT and QTUM are the ones I've been following.