~Mint.com: This site allows you to view all of your accounts - checking, savings, credit cards, investments, student loans, mortgage, etc. - in one secure place. After enrolling, you search for each account that you want to track, input your username and password for that account, and voila: Mint.com displays your most recent balance for that account every time you log in. It totals your net worth, calculates your average monthly spending in various categories such as restaurants, groceries, gas, and clothing, allows you to create a budget, and gives you a sense of where you might be overspending.
You can't make transactions on the site; for instance, you can't move money from your checking account to an investment account, or take money from your savings to pay off a credit card, etc. It simply gathers a record of your assets and debts into one basket.
One thing I like about this tool is that Mint.com will send you notifications about your accounts - for instance, when your monthly loan payment is due, or when the interest rate on one of your credit card increases.
~creditkarma.com: I know I'm not the only person who's ever requested her credit score only to get duped into a pricy monthly credit monitoring service! That's why I like this site: it's free, and it doesn't get all sneaky by roping you into extras that you don't need. Instead, it obtains your credit score from one of the main credit bureaus (keep in mind that the score will often vary depending on the credit reporting agency), provides you with a general interpretation/explanation for that score via a CreditKarma "report card," and allows you to track your credit score over time.
I've been using it for several months now, and I haven't seen anything shady in CreditKarma's practices. Checking CreditKarma doesn't affect your credit score in any way. You can find more information about how this service operates here.