Look at the convoy L2 also a non-side switch light. Atm, there is no extension tube (or 2 cell tube) but there will be with the new version. Take a look at this thread: Convoy L2...Guess who's back???.
Also, look at this supfire L5. http://www.mtnelectronics.com/index.php?route=product/product&path=80&product_id=355
It has a side switch but no extension tube.