The LED "bulbs" I had were dimmable, socket type MR8. The thing is, they still flickered. I think it was something about the dimmer switch itself being unhappy--the flickering was not constant, but it was impossible to stop completely, even at 100% brightness on the dial. My point is, these things have given rise to all sorts of weird incompatibilities that we didn't have before, and I am tired of it. Anything like "Well there are bulbs that will work but you just have to order them from this one guy" is not really a solution--we're talking about lights in a house, not the International Space Station. :) The government has forced us into using technology which is not ready for true mainstream use (as opposed to geek use).
Amazon. I have about 4-5 different brands because I bought several different ones to test colour tone (most "warm white" leds are too cold white for me to want them in my living room).