There are some truly nasty looking pics on this site:
http://www.apautodiagnostics.com/seized ... glow-plugs of broken injectors and glowplugs. Quite a lot of inventive, if abortive, efforts to remove them. The guys that run this place must have lots of kit, and lots of patience!
Do I need to be worried that I found it very interesting and looked through the pics for ages....

Nurse! Nurse!!!