They are blue LEDs with 3.3 and 20ma. I must have something hooked up wrong then because I only have 26 and they are dim. I have three panels. I tested each panel and they are bright. They are all parallel, but I think the problem might be the way I connected the three panels. I would need to make sure that they stay parallel.
In theory, you could put three LEDs per string (string = one resistor plus some number of LEDs in series). At 20 mA per string, you could do 50 strings per amp of PSU capacity. So if you have a PSU with 20A on the 12V rail, you could do 20*50*3 = 3000 LEDs. If you want to continue the madness, you could also use the 5V rail, with one LED per string there, for several hundred more.