All my stuff is covered under my home insurance, and that includes cover when it's not at home too. I have a spreadsheet with my guitars/amps/pedals on it that I keep up to date with details, modifications, serial numbers, values etc. It's scary when you read the totals rows :o
I also make sure my my wife has a copy of the spreadsheet in case something happens to me. She also has the contact details for my guitar playing mates who could help out if it all had to be sold etc.
A bit of a a grim thought, but with the amount of stuff I've got she'd need some help........