Life insurance. The biggest area where I see people over-insured is through life insurance. Most of the time, a person is sold a cash-value life insurance policy as a good retirement savings vehicle. Although this may be good to have from a tax standpoint, by taking out a massive life insurance contract, the insured has just made him or herself more valuable dead than alive.
I watch a good amount of NBC's "Dateline," and it seems as if once a month there is a story about someone who was murdered with the goal of obtaining their life insurance proceeds. Although it is important to have life insurance to provide your family with a source of income in the event of your death, being over-insured can provide an incentive for you to be dead.
And there are so many life insurance riders. While I can't cover each one in detail, I can safely say that riders wouldn't exist if the life insurance company didn't make money off of them. Know which riders meet your unique needs, and steer clear of riders that are too complex or sound too good to be true (because they usually are).
Homeowners insurance. Know that the replacement cost of your house and the market value of your house are two separate amounts. The value of land is included in the market value of your house but should not be included in the replacement cost.
When you insure your house, you are insuring the replacement cost, or the cost it would take to replace your house. Having your house insured for the true replacement cost of your home rather than the value of your home can reduce your premiums.