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.
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We are always happy to work with new investors interested in collaborating with us to make our reserve larger.
I contacted them and inquired about an investment over 100 BTC. but they said that they are currently at capacity and don't accept new investments.