I have an "intelligent" glow driver which is supplied by Nelson Hobbies. Very compact and useful. It senses plug condition and only comes on above a set point if the plug is cooling. It conserves the glow nicad battery (and plug). Definitely worth a look.

I have also used McDaniel units with success.

There are a number of good OBG systems around. I am sure other's will post to advise their favorites!