What options are available for insulating interior walls myself with minimal damage to the wall?
Retrofitting walls with insulation as a DIY project isn't really viable if you don't want to tear open the walls.

The options that I am aware of:


blown in cellulose (they come in, drill 1 small hole in each stud bay, and then fill the bays with insulation)
spray in foam (same general technique as the one above)
exterior foam boards (they remove the siding, insulate with foam panels, add new siding)


Alas, none of them are really DIY.

The only DIY method I can think of would be to take down the sheetrock and insulate yourself, but that would be a huge amount of work and likely not save you much much money in the long run.