Mint.com is a lovely site that offers an incredibly useful tool for personal finance management, and also some general advice on how to manage your money:
Pulled from the above article, a series of "cost calculators" for just about everything you can imagine...
What's the cost of raising a child? Find out here:
What about the cost of moving to a new city?
The "real cost" of a car?
Finally, how long will it take you to pay off that credit card debt?