General information
Currencies
The Dutch side uses the US dollar although the official currency is the Netherlands Antilles Florin or Guilder (NAF), not the same as the original Florin or Guilder from the Netherlands, which of course has disappeared now that the Euro, (EUR or €) has taken over Europe. Many places don't even post prices in NAF. Some do, and in theory, there is a conversion rate between the dollar and NAF, but it is set by the NA government and remains fixed from one budget crisis to the next. Currently it is about 1.80 NAF to the dollar. If you are bad at math, divide the NAF price by 2 and add 10%. If you are looking at a NAF price per kilo, divide the NAF price by 4 to get $/lbs.
The French side currently uses Euros (EUR or €), but everyone accepts US dollars - the question is, at what rate? In the winter of 2008/9, the Dollar buys about 0.65 €, but it has gone from than 1.15 to 0.6 in the last several years. Your credit card is generally charged in foreign currency and you should get a good exchange rate from them, but most have added a foreign currency conversion charge. Some places on the French side only have a dollar credit card account so they convert their currency to dollars and put that amount on the charge slip. There used to be advice here about watching the exchange rate that you get from French-side merchants. It's still true, maybe even more so now, because many of the are offering 1 to 1 in an attempt to keep their American customers. It's just that now, almost every establishment will be offering better exchange rates than your credit card.
Taxis and Buses
Taxis are readily available and quite friendly. They are not metered so you have to trust that they are charging the correct amount, but usually they do because it is too good a job to lose. The set rates are for two passengers and minimal luggage. If you and your fifty closest relatives show up with luggage for a six month vacation, expect to pay a bit more. Periodically, a website puts up taxi fares and then disappears. I have linked to two of them over the years and they both dissolved. The last time we checked, a short cab ride was about $25 for two people and the longest cab ride on the island (ie, halfway around, say from the airport to Grand Case) cost about $40. That's for two passengers and it's $5 more for each extra person. There is a 25% surcharge between 10pm and midnight and 50% from then until 6am.
Buses are usually privately owned mini-vans and come along quite often. The fare is generally $2 and you can pretty much get everywhere on them. But know that they usually stop service at 8pm. Officially, we don’t know anything about Gypsie Taxis. But apparently most locals living in certain neighborhoods do.