Last Friday's rally was heartening, but why did it happen? I am guessing that a drop in oil and a rise in the dollar were helpful ingredients. At $115.32, oil is down 22% from its $147.27 a barrel high, and at $1.49, the dollar has strengthened 11% from its low of $1.60 per euro. But what was behind those moves? Can those factors persist? What happens to stocks if they sink?

The dollar/euro is moving based on relative economic strength and inflation policy. Some think that the dollar strengthened over recent weeks because Europe appears to be heading into a recession and the U.S. has already been in one since the fourth quarter of 2007. If the U.S. is further along, it may begin its recovery sooner.

As far as inflation policy, the U.S. has kept rates at 2%, while Europe appears more likely to raise rates to fight inflation. Bloomberg News reports that European Central bank council member Klaus Liebscher said "policy makers remain focused on the 'worrying' level of inflation." The euro has rebounded to $1.50 on this announcement.

The highways I drove this Memorial Day weekend were relatively empty thanks to people opting for a Staycation. But people I spoke with were wondering why gasoline prices were so high and whether they'll go higher. While USA Today thinks they've peaked, my answer to both questions is I don't know.

But if one source is right that 60% of the trading volume in oil is from speculators, then a rise in the dollar and a drop in consumption would force those speculators to reverse course -- and that would send oil prices plummeting. Here are five things you can do to help make this happen:

• Drive less. Many people don't have the option to do this. But carpooling is an option for many. People can also try to make many stops during a single car trip rather than doing one at a time. And they can try to telecommute more frequently.
• Take public transportation. Much has been written recently about people taking buses, trains, and other forms of public transportation to work. While this is often more time consuming and can be inconvenient. It may also save money and will certainly cut down on your gasoline consumption.
• Ride a bike or use a motorcycle. I know riding a bike would be a major inconvenience for many people. Riding a motorcycle gets better gas mileage than a car and is fun for some. During periods of dry weather these options could work fairly well. But they'd be awfully tough during a snow or rain storm.