Yeah quite true. FB & Twitter are #1 in their markets (Twitter being a true innovation) not b/c they have a few million users but b/c they have 10s of millions

Yeah quite true. FB & Twitter are #1 in their markets (Twitter being a true innovation) not b/c they have a few million users but b/c they have 10s of millions and in FB's case 100s of millions. No one even knows about the #2s in that space. Whereas with 37signals and other productivity apps there is plenty of room to be #2 or #3 or even carve out a nice well paying niche for yourself - all but impossible in an ad supported model where you need that critical mass or you go the way of Friendster..