The London Eye, built for the celebration of the new millennium, is a huge, Ferris-wheel-type observation ride. Taking 30 minutes to complete a revolution, your "flight" consists of one trip to a height of 450 feet and back down again.

You ride with about a dozen people in a pod with clear plastic walls. There's a bench you can sit on in the center of the capsule.  It is very stable, doesn't rock at all.

The London Eye web site has some more information, but it's mostly about booking a flight.