If you're in the mood for holiday nostalgia, the Yule Log visualization might hit the spot. It's free, it's simple, and it's endearingly cheesy -- the flames are the only animated objects in what is otherwise a still rendering of three logs in a small fireplace, bouncing along to the percussion and bass in your tracks. If you regularly stream your own media from your PC to your TV, the Yule Log allows you to recreate its TV-classic counterpart with your own soundtrack.
In the eye-candy category is Phthalo's Corona, which has aged well since its 2004 release. This visualization creates waves which are mirrored under a horizon. At its best, Phthalo's Corona is reminiscent of the hugely popular MilkDrop visualization plug-in for WinAmp, creating frames that look like moving abstract art. The persistent horizon effect is unique among Windows Media Player visualizations, but it would be nice if it could be disabled. Like many Windows Media Player visualizations, Phthalo's Corona doesn't come with any built-in tweaking interface, so what you see is what you get.

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Heading up the best of the psychadelic visualizations is PixelTrip. PixelTrip doesn't do anything new, conceptually -- many of the effects seen from this visualization aren't very different from the ones you'd find in the original classics. Where PixelTrip shines is its ability to be configured, and its ability to produce visuals beyond what graphics cards were capable of when it was released. It won't push the upper limits like a bleeding-edge game will, but if you have a solid GPU in your case, you can crank up the resolution and frames-per-second and enjoy visuals that suddenly appear much more powerful, fluid, and crisp. This is the kind of stuff most people envision when they think of mp3 visualizations, and PixelTrip does it well.