I'm actually perfectly happy with the brightness of the Nashbar 5-LED blinkies. They're quite good if you get rechargeable AAs and juice 'em up every few weeks.

What I need is better reliability... I haven't yet figured out a rock-solid way to attach a rear light to a bike with a rack and no space on the seatpost to mount the light. So I keep breaking and getting new blinkies every couple months.