Parking at a meter in SF costs at least $1.50/hour. You need eight quarters in your pocket to stop for lunch. Who has that kind of change?
Awhile back SF upgraded all its meters to take stored value smart cards. Now, two years later, you can finally buy the cards! The places to buy them were a well kept secret, but recently it was disclosed you can buy them at Muni sales counters. Why not online? beats me.
The implementation seems pretty good; you put the card in a meter, the meter tells you your balance, and then the longer you keep the card in the meter the more (virtual) quarters you drop. Simple enough. I note my non-refundable card is set to expire at the end of this year. It's all a "trial program", you see. I just wanna park!