We have the PRESTO card in the greater Toronto Area, which is valid on trains, buses, and some subways (and I think streetcars) across the region, with more systems being added in further away areas (Niagara etc.). You can't use it in convenience stores, but there has been discussion about this. Mine is set to automatically reload from my credit card, you can also top it up by credit, debit or cash at stations, and cards online.
In London, England, the Oyster card is similar - you can use it on a variety of transport, but again, I don't think you can use it at convenience stores.