Decent Off-The-Shelf 3D Movement Controllers?

Milo_Mindbender asks: "I'm working on a project that involves flying/moving around in 3d spaces similar to what you would do in an archetectural walkthrough. I'm looking for a good and fairly natural controller for moving around in 6 degrees of 3D space. Something like the old 'Spaceball' would be great, but the company doesn't seem to make them anymore. Has anyone seen anything that works particularly well? Ideally, something that only requires one hand and is fairly easy for the uninitiated to learn to use."

Comments

Ever heard of Google?

[The Mayor]

Yet another Ask Slashdot submitter that can't use Google. Here, try this.