Take a look at Kingbright and Stanley. They are the 2 brightess that I am aware of. I use both regularly. Some are so bright they will hurt your eyes to look directly into them.
Lewis — Good point. Some of the traffic-signal types will almost burn holes in retinas. Agilent is one maker of such. agilent.com/Feature/English/archive/E017.html They have had decent prototype-quantity purchases set up through an online vendor.