If 2009 has a buzz word, it’s “transparency.”

The consensus is that we got into this mess because a lot of people didn’t know what they were signing up for: adjustable rate mortgages, arcane investment vehicles, credit cards with hidden fees. People didn’t know because the products were too complicated to understand. Or they weren’t transparent. Or both.

We’ve written about this here on Postcards: Sallie Krawcheck, ex-Citigroup (C) and now the boss of Bank of America’s global wealth and investment management arm, rails against this racket of making financial products too complicated. (“If you can make them complex enough, then it’s difficult to copy them,” she says, explaining big business’s motivation). She calls for greater simplicity and transparency to level the playing field for consumers and investors.

The Internet can help level the playing field too. Last week, I met with the Peter Pham, the CEO of BillShrink.com, a Redwood City, Calif.-based start-up that aims to bring transparency to all your hard-to-figure-out bills. Research shows that 80% of people overpay for credit-card and cell-phone services. BillShrink claims to have found savings of $225 million for the site’s 650,000 U.S. visitors in July.

Pham, who was an early employee and head of biz dev at Photobucket, a photo sharing site that News Corp. acquired in 2007, explains the appeal: “The idea is that you don’t have to ask yourself when you get your bill, ‘Am I getting ripped off?'”

BillShrink, which raised $8 million from Bessemer Venture Partners and Trinity Ventures, started chasing the problem last year, focusing first on cell phone bills. You might have seen T-Mobile spokeswoman Catherine Zeta-Jones on TV, offering wireless customers “mobile makeovers.” Those makeovers come courtesy of BillShrink.

Using algorithms that monitor more than 10 million wireless plan combinations, BillShrink analyzes your phone bill to tell you which plan and phone give you the best value. BillShrink provides the service to you for free. The company gets a commission for its referrals–which, CEO Pham vows, are unbiased.

If you try BillShrink, you’ll get all kinds of data about your cell-phone behavior. For example, I learned that 72% of my minutes are spent calling the same five numbers. (You lucky people know who you are.) I also learned that I talk most often at 8pm (when I’m walking home from the subway after work).

After it offers this analysis, BillShrink gives you a list of cell-phone plans and shows you how much you’ll save by switching, taking into account the cost of breaking your contract with your current carrier. It turned out that based on my habits, T-Mobile does have the best plan for me. But as soon as I used the filters to tell BillShrink that I have an iPhone and am therefore married to AT&T , I got word that I was already on the best plan.

Eager to tap new markets, Pham has expanded BillShrink into tracking more than 200 credit cards, to make sure you’re not getting taken advantage of there. The BillShrink site has a “Credit Card Bill of Rights” that reflects new credit card legislation (some went into effect last week) and tells you if your cards are complying.

A “gas station” comparison tool is in beta. Next up: Savings & CDs. BillShrink won’t stop trying to help you until you understand exactly what you’re signing up for. Making the right choices from there is all up to you.