I have a single speed / fixed gear that I use mainly for my commuter bike. It has the option of being a fixed gear, or flipping it over to a free wheel. I use it with the free wheel.

I love riding that bike. It feels so comfortable and carefree. I really enjoy the quiet and simplicity of not shifting. I call him my "easy breezy sweet little single speedy". It's perfect for tooling around the city. There is only one hill on my route back home that I sometimes stand up for - and even that's more for just a position change, not because the gearing would be too difficult for it.