Matt Mets points us to this DIY wireless flash trigger project. Very cool photography hardware, and you can make it yourself! Specs:

• Synchs at up to 1/250th of a second
• Approximately 30-meter range
• Triggers through walls and windows
• 4 groups of adjustable flashes
• Remote power level adjustment for “old” flashes (e.g. SB-24)
• Cost of parts ~ €50
• Open source software

Includes schematics, source code, etc.