1 x hairdryer
1 x can of "air duster"
1 x soft cloth

Procedure

warm dented area with hair dryer, turn air can upside down and spray dented area with 'liquid' air, wait until dent has pulled itself out, wipe residue away...

http://www.youtube.com/watch?v=wt9BnXFHCfo



never actually tried this... but jus tthought its free, so probably worth a go...