Courtesy of my friend and a great mortgage broker Jenifer Miller, comes this list of how long to keep documents:
Three months Credit card statements, insurance bills, paycheck stubs, utility bills
After your bank ATM receipts, deposit slips, purchase receipts
statement comes
One year Cancelled checks and check registers
Three years Bank statements and tax returns
Longer Insurance policies, legal documents, military documents, mortgages,
records for home improvements and warranties
Lifetime Automobile titles, inventory of home and wallet, birth/marriage
certificates, property deeds, stock certificates and trust papers
Of course, your situation may differ, but this is a good outline to follow.