It is an interesting question, I don't know of a service that allows investors control over their invested funds (it might even be illegal in some jurisdictions) but the most obvious answer is services like crowedcube or kickstarter.
Though we also had a plan to enhance Bitcoin VCs, and allow the bitcoin community to "follow" VCs, if you look at the Angor spec we have what's called a "Lead Investor" mechanism (an investor that puts big money) which allows others to follow them, if lead investor pulls out to penalty anyone invested under them will be able to take their funds without a penalty.
This means that big investors lead the way but anyone else can benefit from their investments without needing to trust your bitcoin with anyone.
