Treadmills are more than just a device to make music video go viral. Sometimes, they're useful for exercisin' and other stuff too. For example:

Omni-Directional Treadmill

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We're one step closer to the Holodeck, folks! Here's the Omni-Directional treadmill that allows a user to walk or jog in any direction of travel in a large-scale virtual environment.

The approach above by Virtual Space Devices (here's another clip) seems to me to be faster than the CirculaFloor moving tiles or the Virtual Reality Roller Shoes, just as fun as the VirtuSphere's giant human hamster ball, though not as good as the fake room/moving floor you've all seen in Jamiroquai's Virtual Insanity music video.

If you have a diabolical mind, the first thing that probably came to mind is that it will make an excellent trap: how do you get off a functional omni-directional treadmill?

Ice Skating Treadmill

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No ice? No problem with the Woodway skating treadmill. The surface is made from slats covered with viscoelastic polyethylene that simulate slippery ice.

Anti-Gravity Treadmill

The AlterG Anti-Gravity Treadmill can give you a lighter-than-air workout - reducing your bodyweight up to 80% - all you have to do is put on puffy rubber shorts:

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It's not cheap though, the AlterG will cost you $75,000 - but it's probably worth it, especially as a rehab equipment for patients recovering from surgery or injury and exercise for pro sport.

Treadmill Desk

Working on your desk AND losing weight at the same time? Forget sitting on yoga ball at the office, this is the way to work out at work. Behold, the Treadmill Desk by Dr. James Levine:

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You can buy various treadmill desks on Amazon, or you can build your own cheaper as Instructables founder Eric Wilhelm did.