The Mac may be in the spotlight these days, but Windows may boast the broadest access to freeware and open source tools for live visuals.

The latest edition: VisualJockey, as pointed out (alongside other free Windows tools) by beatfix on comments.

VisualJockey: Real-time Animation

You get a pretty powerful set of tools in this app, first introduced in 1999:

• Full Windows support, including Vista
• Alpha support throughout; image, AVI, QuickTime file format compatibility
• Global keystone capability
• MIDI, multi-monitor support
• Compatible with FreeFrame plug-ins (open plug-in spec for visuals)
• Sound beatmatching, internal LFOs with lots of waveshapes
• Generators for particles, patterns
• 2D color filtering, effects, blue screen
• 20+ transitions or custom bitmap transitions
• 3D support for 3DS import, primitives, 3D animation
• Export to AVI (which means it can double as an editor)

In fact, VisualJockey’s approach I think is unique — a set of tabs controlling different approaches, a hybrid blend of other interface paradigms. Want a timeline? A reactive sound system? A modular, generative 3D patch? It’s all in there. The UI is decidedly retro, and you get more flexibility from true modular patching environments, but at this price, if you feel like you want another tool in your belt, it’s hard to resist. And with export, this could be handy to have around alongside your existing tool of choice.

But VisualJockey is just the start — here are a few more from beatfix (and me):