'Store credit' option
Well there is this cool 'Store Credit' rune that I find really interesting. However what might be even better if added to the game, is allowing champions to leave gold in the fountain for other to use, maybe even give it some interest over time spent unused. I think all strategy games that include a monetary value allow trading it within teammates, I don't know why LoL doesn't.
and such are already trash tier at. Also it won't be 'expected' from anyone to donate gold, also there could be a scaling cap over time elapsed.