There are two different parts of the Federal Aviation Regulations to consider. Part 91 is what most private pilots operate under. Operations under Part 91 are not allowed for compensation or hire. This part specifically excludes air taxi operations and Mr.Elliot is correct. Any private pilot who charges anything more than an equally shared expense will be in violation of the commercial regulations.

So, you can take someone for a ride, as long as you aren't paid more than an equal share of the expenses. The FAA will not allow you to include amortization, insurance, upkeep or anything else in the calculation, so it basically amounts to splitting the gas and incidentals for that particular trip. And the FAA is watching this like a hawk.

Part 91 allows commercial pilots to do sight seeing within 25 nm of a based airport non-stop, will not allow even commercial pilots to act as jitney drivers unless their airplane and they have passed Part 135 muster.

Part 135 is the air taxi regulations. There is a provision for a single pilot air taxi service, and the regulations are restrictive. They require a commercial pilot certificate, extra inspections (100 hour inspection), commercial insurance (mine runs $775/year for private personal and business use, when I ran an air taxi service, the insurance ran $2550/year for a 4 place single engine airplane.) You have to have FAA approval and a flight check and a letter of authorization from the local FAA Flight Standards District Office.

We developed a "ride board" at ARB for people looking for rides home on weekends, university breaks that pilots could check, and pick people heading in their direction. Great benefit for university students looking for weekend rides home. It fell out of use when it got moved to a little used room at the airport.

When the state tore up every road between Ann Arbor and Detroit and commute times skyrocketed, I started flying from ARB to DET and kept a junker at DET. Before I knew it, I had 3 pax and we "airpooled." There's another group of "airpool" commuters in LA.