I have a few Planetbike Blaze 2 Watt Micro and find they are a great product:
Blaze 2W Micro - Black




Cree 2 watt LED
High and low power beam along with Superflash flashing mode
Highly visible, even in daylight
Optically-advanced lens provides superior beam pattern
QuickCam™ bracket mounts, adjusts or removes without tools
Up to 64 hours runtime (flashing) on 2 AA batteries (included)
139 Lumens