they make bar extension (s)(?). I think that's what they are called. it's alike a short broom stick that mounts to your bars for additional accessories. I usually see them mounted in front of the current bars but maybe you can mount it vertically

try to find the thread about bicycle cockpits - lots of pics!

stuff like this:

see the Nitto Lamp Holder 9scroll down)
http://www.peterwhitecycles.com/light-mounts.asp

and the ViewPoint Spacebar
http://www.buzzillions.com/reviews/v...acebar-reviews

http://www.adventurecycling.org/foru...p?topic=4575.0

http://www.lickbike.com/productpage....=%273220-00%27

http://www.wiggle.co.uk/p/cycle/7/Mi...ion/804758424/

http://www.amazon.com/Minoura-Space-.../dp/B000BMUF1G

http://www.ruscelli.com/biking_fenix.htm