Make:

Design news has their latest "Gadget Freak" up, make a 40-LED bicycle light - "To see and be seen after dark on his bicycle, Bill designed this 40-LED light. He configured a 555 timer IC to generate a continuous on/off timing cycle to alternately flash two groups of 20 LEDs. The device operates on four AA batteries, keeping things bright for even the longest night rides. You can extend battery life with a second circuit Bill designed that uses a short duty cycle to flash a single group of 30 LEDs ." [via] - Link.

Related:

• LED projects @ MAKE - Link.
• Bicycle projects @ MAKE - Link.

From the MAKE store:


The MiniPOV2 is a persistence-of-vision device that rapidly blinks 8 LEDs on and off so that when waved through the air, an image or message appears to float in front of the viewer.
MiniPOV in action. The MiniPOV2 as an easy-to-build demonstration showing how microcontrollers work. Easy to make, inexpensive, and simple. This little kit teaches several not so little lessons:

• How to solder
• How to assemble simple kits
• How to program microcontrollers

The kit includes a Microcontroller, sockets, resistors, LEDs, connectors, a battery case and a printed circuit board. Add some basic tools, a PC with a parallel port, and a little programming, and the MiniPOV is ready to blink out your deepest thoughts.

Get one now at the MAKE store - Link.