Update: I now use Mint.com in place of Yodlee Moneycenter. It has come a long way since I wrote this post.
Yodlee Moneycenter it is an online application that allows you to group all of your bank, credit card, investment, loans, and even reward accounts in a single application. If you have more than a few of accounts at different institutions, this can be a huge convenience and time-saver. HSBC's "Easy View", Bank of America's "My Portfolio", and Wachovia's "One Stop" are all themed versions of Yodlee, but anyone can use it free at http://moneycenter.yodlee.com.
Yodlee categorizes your transactions and gives you a chance to set up and manage a monthly budget for each category. You can also set up email alerts for accounts reaching a minimum balance, a CD maturing, large withdraws/deposits from/to an account, and many others. There is a net-worth tracker, which tells you the overall worth of all your assets minus any liabilities. Monthly records are kept so you can see how your wealth is changing over time.
Most people are probably a little hesitant to add all their accounts into an application like this, but let me ensure you that Yodlee has a strong focus on security. A few months back they also added multi-factor authentication.
I have been using Yodlee for about a two years now.Yodlee is free; you can register for an account here.