Money

The Indonesian currency is is called Rupiah. Automatic teller machines (ATM's) are available in the bigger cities throughout the country. A credit card from Master Card or Visa can be used for paying almost everything. If you want to change money bring US dollars, traveler cheques are not always accepted.

Bargain

If you want to buy something, never forget to bargain ("tawar" - it's a national tradition). This is even true when you want to exchange your dollars for rupiahs at a bank! Even in shops with a fixed price ("harga pas") you can have success.
Don't overdo it however and never loose your temper. Bargaining is always done with a smile. What always is a nice thing to do is to bargain your pisangs (bananas) down from the original 10 cents to 8 (this is often what you are talking about) and just pay the 10 cents. This is always good for a friendly conversation.

Post you holiday cards

When sending your cards to your relatives and friends oversees, it's best to bring them to the post office yourself and ask the man (or woman) behind the desk to actually stamp the cards. A lot of stories are known of post cards never to reach the destination, because somebody at the post office had other things in mind for your stamps.
You could also check your hotel reception. They don't want their name ruined, so they will make sure nothing happens to your cards.