Testnet peers list (with IP addresses) There are some services to get the list of current known peers,
like those offered by 21.co or Blockchain.info
but I can't find anything similar for the Testnet network.

Does anybody know a Testnet peer list?

Actually, it is also very hard to find any IP testnet address.
Is there a reason for that?
Just use a testnet dns seeder.

Type this into your terminal:

dig A testnet-seed.bitcoin.jonasschnelli.ch


or 

dig A seed.tbtc.petertodd.org


for IPv6

dig AAAA testnet-seed.bitcoin.jonasschnelli.ch