This took all day. Lots of little bits of colour, gradients & transparencies. I'm not sure I'm totally happy with it, but I've spent 10 hours on it today and it's reached the point where I can't even tell if it's good or not because I've been staring at it for too long. There's loads of detail there if you want to zoom right in. Have a look see.
This on the other hand took no time at all but I thought it looked pretty cool.