Emoney

A year and a half later has seen me using a BCA Flazz and a Mandiri etoll card for a wide variety of transactions from simple shopping in Alfamart, paying toll road charges, and even car parking in shopping centres.
The toll road cards are generally used at automatic toll gates (GTO), and they commonly have no or very short queues when the cash gates are jammed. I strongly recommend them for any regular toll road user.

These cards have proven very useful and have no serious issues to complain about. Some places have problems with their machines from time to time, but that's not much of a pain and there has been no attempt at fraud, so I have to come down in favour of using these cards.

There are many such cards available now, but the BCA Flazz and etoll seem to be the most popular, thus the most useful.
One other note - The banks are trying to get exclusive access to some events such as the motor show in BSD a few weeks ago, meaning all transactions in the food courts had to be done using an etoll (or other Mandiri card). The two I have pretty much cover me for everything and save all that messing about with loose change weighing your pockets down.