Credit card and cash advances available in most tourist areas. Most shops accept plastic for an additional 3 to 5 percent surcharge. Visa, MasterCard and American Express are accepted by most bigger tourist oriented businesses.
Just sign for the amount in rupiah and the bill is converted into your domestic currency.
You can also get cash advances on major credit cards over the counter. You may need to shop around, since the cash advances over the counter do attract a commission.