As above said, bitmixer.io is my only known mixer. If you want even more anonymity, try to search on deepnet. (CAUTION: Risk at your own, when you try at deepnet)
~Rude Boy
Deepnet mixing seems very risky to me as well (also you have to know how to enter the "World of TOR", which I do not).
A much lower risk way to mix your coins (beyond bitmixer.io) is to use SharedCoin (blockchain.info's mixing service). I try to pay attention to BTC mixing threads and comments here, both SharedCoin and bitmixer.io work well for me.
Follow instructions! <===For extra (apparently) security, you could mix twice (in sequence SharedCoin then bitmixer.io for example), that would probably be very hard to crack. Probably
.gov is about it...
