So yeah what I am about to say here assumes that "find a new home" = reinvent the idea/ Breathe new life into it.
You know there is a saying about how one doesn't pour new wine into old bottles.. they put it in new ones! Even so, I think that what you guys did when twitter startups began to heat up was awesome! It was an opportunity and you took advantage of it. However.. I think the general problem here is that your missing the vitality incentive factor.. aired with a chicken and egg problem (the whole brands advertising won't really happen with out the people.. then in turn the charities won't get anything.)
So the solution is simple.. It all comes down to what you believe in. Whatever it is that you believe in for this.. the idea needs to mature to give proper incentives for people to take part.. also it should have ample virality included (you had that going with the @twollars thing.) problem is i don't think people may have clearly understood why they were doing it.. and then furthermore.. how much are the charities getting for the effort of tweeting that out.
What I think about the way things should have worked out is something to the tune of.. Business --> Users --> Charities instead of your current model deal (Users <--- Business --> Charity).. which also looks kind fuzzy it should be easier to grasp.
So my point is if it were something like Businesses sponsor the process with their products (like free service/software/products) let's say per month.. then users pay to be part of the process.. in which their money goes to charities. then at the end of every cycle users win products from the businesses that participated. Now the only thing left would be to find out a systematic way to get twollars involved for instance you can have a set number of charities that are in the event for that month.. in which different prizes are available from the business sponsors and one could @twollars to a specific charity to spread awareness? to be honest the most difficult part of it seems to be the implementation of the @twollars making that meaningful devoid of money/incentive will be difficult..
Furthermore you have to give incentive giving out more twollars.. it just does'nt seem convincing enough to me unless you add some means of tracking twollar karma on your website through various means and then using the karma (gained by spreading awarness/activity/positivity) to get rewards from the business sponsors.
/end wall of text
What exactly where you thinking about?