I don't mean to seem unscrupulous, but the process of raising money for a missionary is not unlike what is done by a sales rep or a realtor: you have to keep yourself at the top of people's minds or the money dries up.
In that regard, software like facebook and even contactually are invaluable.
But, it seems to me, there's even more work to be done around custom platforms.
That said, how are you going to make money? Take 30% off the top? 10%? People (rightly) want to make their money go as directly as possible and so often won't even pay by credit card because you lose 3% in fees.
These platforms do cost money to run and not every church has someone on staff qualified to host an open-source solution. So if someone doesn't create hosted services that are financially viable, everyone loses out.
I also know several genuinely good people who desire to go to seminary but simply aren't able to take 3 years off of work (because they have families etc.). Of course you always have the risk of folks taking advantage of the system, but in the success / genuine / majority case, I feel that a kickstarter for people who want to do domestic ministry is a real need right now.
If anyone is interested in working on (and working through) these kinds of problems, drop me a line. My email is in my profile.