Nothing is more annoying than a rubbing rotor. Especially when you're looking for the last few watts that you want to save and not leave lying on the street. This small but very smart alignment tool from Park Tool can help. This can be used to straighten the bent disc in most cases. First with very little force, then maybe with a little more and if all else fails, then with the short slot and a real lever.
You can see exactly how this works in this video. Including a bockwurst that dies in it and many other useful tips on the ever-popular disc brakes:
Laser cut solid steel covered in vinyl. Like everything from Park Tool, really good heavy quality and made in the USA.