I posted earlier about my cold blue LED Christmas lights, and how I'd learned that the trick to warming their light colour is just to apply some nail polish in an orange or yellow colour. Recently I was at the mall and spotted some horrible orange nail polish. After wondering to myself why anyone would paint their nails that colour, I remembered the lights.
When I got home I tried the polish on the garland in my hallway and to my great excitement, it worked.
After. It's subtle, but they are much less garish.
The (slight) downside is that when the lights are off they are orange coloured. But no one really looks at Christmas lights when they aren't on, anyway. I'll be painting my other lights after I take the tree down.
(I'm kind of curious to get other colours of nail polish and try them out... you could have a whole rainbow of lights!)