if you mean exchange, then basically all famous one support multisig address, or you mean merchants too? but as far as i know everyone should support them they are not exactly a new thing...
kraken use them for example
kraken use them for example
OK, let me explain.
Everyone can create p2sh/msig address from the private keys he owns.
I am not interested in it.
I can create p2sh addresses myself.
I do not need the web-services which create such addresses from user public keys.
I want to research some statistics how p2sh/msig addresses are used for several parties.
For example, some kind of betting systems, where one key belongs to Alice, second key belongs to Bob and the third key belongs to Oracle.
I want to create list of such services.
