LED Light Bulbs
Perhaps "dimmable bulb" would be more accurately called "hummable", because CFL and LED light bulbs that I have tried often have an annoying hum when used on a dimmer circuit. Below is data from recent experience (2014 Jan 4-11) with LED bulbs and dimmers that may be useful to others wanting to have dimmable no-hum bulbs.
The data suggest that bulb humming is a property of the bulb, not the dimmer. The CREE bulb hummed significantly more loudly than the Philips. The FEIT bulb seems to be silent, even for my family member most sensitive to humming.