What is an easy way to power a 3.3v BMP-180 barometer board from a 5v Arduino Nano?
Here is the solution I settled on:  a small part that will step 5 volts down to 3.3 volts.  The price is right, but it will be shipped by the slow boat so will take a month or so to receive.

5Pcs 5V to 3.3V DC-DC Step-Down Power Supply Buck Module AMS1117 LDO 800MA

http://www.ebay.com/itm/5Pcs-5V-to-3-3V-DC-DC-Step-Down-Power-Supply-Buck-Module-AMS1117-LDO-800MA-/261983164332

It has 3 pins - Vin, Vout, GND.    Easy to hook up.

Upvote to everybody for the discussion.