Organizing your personal documents is very important especially when you needed it most. Among the personal documents are:
House titles and insurance
Financial documents such as bank records, investment documents (if you have any), credit card documents
Health related documents such as health insurance payments, previous laboratory tests, medical results, doctors prescriptions
Travel documents such as passports
Important photos but nowadays photos can be saved digitally in hardrives and online storage websites
If you are a parent, it is advisable that atleast your children knows your documents in case of unexpected things happen.