Is this maybe interesting for you?
https://merge-rewards.com

I'm still working on it. Actually it is a living prototype, so to say. Some of the claims are not really true yet. You cannot withdraw in BTC or ETH and so on but I'm currently implementing this with the help of the blocktrades API. (UPDATE: Ok, BTC works now!) Possibilities to sponsor projects and thereby invest in STEEM will also be available soon.

What do you think?

Intro post: https://steemit.com/introduceyourself/@merge-rewards/merge-rewards-beta-root-post