Call my best friend with goodbyes and instructions while also throwing away anything I’d be embarassed for people to find, and then cuddling with the kitties. And I’d double check and make sure the toilet’s flushed and my TV isn’t currently tuned to a shopping network or E! or something. 
Run and buy some cigarettes (I quit years ago and still crave the damn things every day), then chainsmoke while I wrote letters to everyone I love.
Sit in a corner whimpering and muttering “Why me?”
I’d make a bet with someone that I was going to die in 10 minutes and ensure that I won it.
Call loved one. Smoke cigarette. Meditate to clean mind (while smoking).
Glib answer: read FMA. I only just started that manga, dammit.
Slightly more serious: call my fiancé, say goodbye to him and then to my family, and pray. Pet the cats.
Having been in a couple near-death situations last summer, I’ll give you the honest answer: go white and get very quiet, and possibly shake a little.
i’d call the ambulance.
Cut myself up a little and write “FOR THE HORDE!” on the walls in my own blood. Then get on the phone about a life insurance policy, ASAP.
There is one person I’d like to share that last ten minutes with, because,
Motherfucker, it’s payback time!
Then I’d go out with a smile.