Bitmixer.io sounds like a nice opportunity, but their investment is full and they don't accept no new deposits. 
i think it is a good opportunity too but the problem is the minimum amount of investment is 100 BTC.their website doesn't say anything about not accepting new investment.
Quote
We are always happy to work with new investors interested in collaborating with us to make our reserve larger.
100 BTC? C`mon guys, who would risk 100 BTC with unknown and unreachable people.
If they steal 100 BTC whan can you do about it?
Plus its just stupid, why would you invest 100BTC in it when others let you invest as little as 0.001 BTC, its just silly in my opinion