Has anyone explored other anonymity strategies aside from input/output mixing?
-bm
I think that's the most popular as no one is about to change BTC core to include anonymity at a protocol level. Do you have any other projects to review? Input/Output can always be correlated but it would take QC power to do so.
The fact is you can get fairly good anonymity simply by putting your coins on an exchange that doesn't require ID, and then transferring it out to an address that you have never used. If you use Tor for all your interactions with the exchange website, then the coins are mostly untraceable. Any exchange in the US, Singapore, most of Western Europe does not offer you anonymity. If you issue the outgoing payment TX using Tor as well, the payment is mostly untraceable. It's possible to automate all this in the wallet.
I don't know of any ideas that are not in this class of input/ouput mixing although it may be possible to implement something using
cryptographic blinding.
-bm