Idea for a Crypto currency... or does this already exist?

So I have been looking into Crypto-Currencies and there doesn't seem to exist a service that I want. I want to invest but to brutally honest I'm a coward.

What I wish existed is an app based on the block chain that essentially functions as a online exchange of Crypto-Currencies. but one in which all the traders performances is tracked so you can see how successful or unsuccessful a given trader is. On this app I would be able to invest an amount of currency and link it to a trader, who has a good performance rating. The trader I link to would get a cut of my earnings in exchange.

:)