Here's an idea.
Why dont philantropists donate money to the bitcoin community to support the efforts.
The money is divided equally among outstanding bitcoins, thereby increasing the average value. (EDIT: In effect, you can just put a high priced bid into the market place, and let it filter through)
Initial discussion here:https://bitcointalk.org/index.php?topic=549.0
Donating money to keep the price of bitcoin inflated doesn't sound like charity because it will mostly benefit the RICH! The people that have the most bitcoin will benefit the most, and that's not really the point of charity.
It would be better for philanthropists to teach the un-banked how to use bitcoin to help them facilitate their banking and transactions because micro-payments can be done so easily.