wow, http://www.superbrightleds.com sells some really neat products.
I think I will order some white LED's and some diffused 360deg blue LED's and do some more experimenting.
Some more details on the the gauge lights pictured.
The green is of course the stock lighting
For the blue, I first removed the green lens then installed 4 super bright blue LED's (2600mcd, 468nm, 30deg) 2 on the left and 2 on the right as evenly as I could get them. I used 4 LED's just to keep the light as even as possible on the face of the gauge. I used a little dab of some good clear silicone to hold them in, which seems more then adequate. I then carefully routed the wires where they would be clear of the gauge's mechanical parts and out the original light bulb hole. This worked ok but when I do it for real I may drill holes and install snap in led holders.
Also to help the light reflect on to the face I painted the back side of the front of the gauge with a quick shot of krylon gloss white. But I did that before any photos were taken so the picture of the stock green is after paint.
Another thing to note is I am powering the gauge from a 12vdc power supply so it would be like the dimmer switch is on full blast.
I was also toying with the idea of installing the LED's in sets of red, green, blue. Then wiring each color to its own dimmer switch. Then by adjusting each dimmer switch I could effectively change the gauge light color... maybe... kind of like what they have going on in the new mustang. But that is 3 times the parts and wiring.