I used my plastic welder to fix the Chrysler headphones that came with the built-in DVD player in our 300. My kids have slammed the car doors on them enough times that they were crunched into oblivian. No glue really holds them so I just used the plastic welder (really just a soldering iron with a flat tip) and melted them back on to the metal head band.
They are still holding up after several re-repairs over 7 years.
It sure beats paying another $300 for a new pair from Chrysler.
Here's the one I have. You can buy different plastic welding rods depending on what you have (probably ABS) but a lot of times you don't even need the welding rod, you just heat and smear the existing plastic back over the cracked area.
http://www.amazon.com/Urethane-Suppl...ef=pd_sxp_f_pt