I'm willing to hold it, with 100% reserve in cold storage, free of charge (I am hoping I would get improved reputation and more trust out of this). I've been around for quite a while, held that amount for Bitcoin100 with no problems, and like to think I'm fairly trusted. I would store it in my Armory cold storage wallet (offline signature transactions, so zero chance of hacks), and would prefer to make the address public so that others can see there's nothing funny happening with the money, as well as that any requests to send it back are verifiable. I would also prefer to have an address that a paper backup in a sealed envelope can be automatically sent to should anything happen to me.
P.S. I also have a few thousand BTC in my personal accounts, so I've "dealt with far more BTC at one time than what I'll be holding for the forum."
This should be a requirement for all partial key holders, otherwise the disappearance of one party could make a grouping of funds inaccessible. Is is possible to perhaps make some kind of "time lock" storage which will automatically release the funds back to a designated central account unless the trusted key holders reset the time period of the lock on a say monthly, or annual basis?
In this way the only circumstance in which the funds could be held up is by willful defiance of the partial key holder. Is there a way to divide the keys so that say 5 out of 6 partial key holders must cooperate rather than all 6 to reduce the chances of a rogue person holding up forum funds?
"Send Bitcoins Into The Future!"
https://bitcointalk.org/index.php?topic=128581.0
Rather than a 2 of 3 scheme, maybe a 5 of 10 scheme. Hand out 20 keys to well known members (with 10 real, 10 fakes). Don't announce who holds any keys. This prevents collusion, as if forum members start asking around if they hold a key, alarm bells may go off and report back to theymos.
If something were to happen to theymos, everyone can turn in their keys to whatever authority is present at the time.
Also this^
Making diversion keys is probably a good idea. In this way any attempt to steal the funds might be discovered early and thwarted before actual funds are stolen. Additionally a 2 of 3 scheme can help prevent loss because of a user disappearance for whatever reason.