Extra brake light?
 

I've seen these extra brake lights that you can attach to the rear of your bike helmet. They're wireless as they get a signal from a bulb sender in your rear light cluster.

Anybody got one?

Either that Or I'm thinking of adding 2 red LED lights to the back of the bike to make it more noticable from the back.

yes to both.

the light strip is designed to affix to the back of your helmet and runs on 4 button batteries, works well, the only down side is it comes flat and is made of a rubber type stuff, it sticks on the helmet with a sticky pad, this can come off a bit at the ends where you have to bend it. batteries lasted about 4-6 weeks heavy use.

wired in LED's are great, just make sure you wire them in the right way around, because unlike bulbs they only work one way (long leg normally positive).

Cheers Mark.