I have a regular flip flop hub with a single speed and a fixed cog, but if I'm going to coast I have decided I want more gears.

So, has anyone seen, or heard of an internally geared hub where I could mount a fixed cog on the other side?

Alternatively if there is an internally geared up that can lock that might work too. However, I am used to a gear ratio of about 42-14 and wouldn't want something drastically easier or drastically harder.

Anyone know anything?

(this is double posted from single-speed and fixed gear, please don't shoot me)