You could also just put some paint on the LEDs. Did that on a bright led on an usb stick that I use in my car stereo.
That reminds me of the first Electronic Music gig that I played. It was in Jodrell Bank Planetarium (in 2000) and it was fiercely dark in there, so I had bought sets of false glasses that had a small light on each side (I think Orbital used something similar) - all three of us had them on. The light from those things was so strong that we had to find a way to tame it, in the end we had to colour the bulbs with green marker pens.
A few people took pictures and in all of them we left green flare trails as we moved our heads. It was quite a talking point, what were these eerie green lights...? Some people even enjoyed the music