A few years ago during a Utah trip, I burned a hole in my "beater" down coat I use for car camping. (We we were doing a trailhead bivvy before a trip. I leaned over the camp stove and singed it. Doh!)
I put some duct tape on as a temp measure, stashed it in the car, came back from the trip and went to an outfitter in Moab and bought this tape:
When I arrived back at home, I gently washed with a damp cloth the area around the gash, dried the area and placed on the tape. With an iron on VERY LOW setting, I gently ironed around the edges of the tape.
I still use this jacket regularly as my beater down jacket, the feathers have stayed intact and the repair has held 4+ yrs later.
(As an aside, pay $55 on clearance for this jacket and has been quite the work horse for me http://www.trailspace.com/gear/ems/glacier-down-jacket/ No longer avail. )