I recently bought a new LED bike light to see by while riding - actually a MR16 halogen format 12V light from Jaycar (part ZD-0315) and wanted to see how it compared to my existing lights. While it's not as bright as a 20W halogen, it's definitely enough to ride with and a lot better than my existing LED lights. To give a reasonable comparison I put the camera in manual mode and kept the exposure constant.
The lights are: Jaycar ZD-0315 with a 10AA battery pack (home made), a 20W halogen rig (home made) running at 10W, a Cateye HL-EL100 with 3 LEDs and 4AA batteries, and two 2AA blinkies just labelled "Smart". See final photo for handlebar shot.
Click on any photo to see a larger version