This is one of those things we're sure we've blogged before, but we haven't. (Stephanie did mention it during the Green Cure.)
American Pride is a reasonably priced, high-performing green synthetic paint produced by the same company that makes Mythic Paint.
We have a fair amount in our Portland house and it's holding up well.
We particularly like how the eggshell trim is holding up—not too shiny, yet still easy to clean.
The paint is Green Seal certified, which means the ingredient list is checked for prohibited materials, the manufacturing plant is audited, and the paint is tested to make sure it meets Green Seal's standards. American Pride is manufactured in Chicago and distributed from a company in Mississippi, so there's a fair amount of transportation involved. Because paint is heavy and therefore carbon-intensive to truck, a locally-produced paint may be a greener choice. (We also heard second-hand that resins in the paint are made from soy, which wouldn't be surprising given the escalating cost of petroleum, the usual source of the chemicals in a can of paint.)
ecohaus sells the paint online for about $30-$40 plus shipping; if you're a Bay Area neighbor, Berkeley's EcoHome Improvement sells all colors and all sheens for $38.99. If you're elsewhere, there's a store locator function at the American Pride website.