Death in Service AVCs
Death in Service AVCs used to be quite a good deal. I paid about £8 per month through my pay, which guaranteed my wife '4 x my salary' if I died (she would have got 1 x salary w/o DiS-AVCs). However, I think that the new Services compensation scheme guarantees 3 x salary now (if you are on AFPS75) and that you can bump it up to 4 x salary for a small amount. Your PSF/UPO/Admin Office should have the gen.
Then again I've been out for a while now and things may have changed.