If you drop your rappel device or just forget to bring it, knowing this variation of the old-school carabiner brake can come in handy. (Try to avoid a Munter hitch unless you really have no other options, it can seriously twist your rope if you do it wrong.)
Climbing tips and navigation resources
Alpine Savvy
How to (almost) never drop your belay device — Alpine Savvy
Adding friction to a rappel — Alpine Savvy
Climbing How To: A carabiner brake for abseiling / rappelling
Adding friction to a rappel — Alpine Savvy
The no twist Munter hitch rappel — Alpine Savvy
Rock Climbing Instruction
Grigris for alpine climbing — Alpine Savvy
Transformers! Your ATC belay device is also an ascender — Alpine Savvy