What services are available to publicly raise Bitcoin funds?
I'm considering setting up a Bitcoin fund that would accept BTC donations. If the fund doesn't reach a certain value after a time, I'd like it to refund the BTC. Also, I'd like to give donors the option of withdrawing their donations once a week. It needs to be safe from hackers (eg. the BTC are stored on MtGox with Yubikey protection), and transparent.
Obviously I don't want to use a regular bitcoin wallet address as the public wouldn't trust it.
Does anything like this exist?