If you want to make unusual electronics project to collect donations then an Advice Machine is good idea. Nick Johnson has built nice Advice Machine based on Raspberry Pi. The project uses coin acceptor from eBay, model number CH-926, a 2×16 LCD to display all status messages and thermal printer to print the advice. Simple Python program is written to scans the GPIOs activity and drives the display and printer.
Here is how the machine works. Insert whatever quantity of coins, press a button and get some advices printed via small thermal printer. The quality of the advice you get depends on value of the coins you put in. More money gives more in-depth fortunes and more interesting such as quotations, while a small amount gets you platitudes or terrible jokes.