CHICAGO — Dan Hassenplug's monthly expenses used to include around $300 for lunch and three or four books bought from Amazon.com. Now he's plugged into a new breed of social network that helps him manage his finances.

"When you see a graph that says you averaged $10 a day for lunch — about $300 for the month — well, that's a lot of money," said the 24-year-old design manager from Geneva, Ill. Now he's cut that expense in half by packing a lunch most days and buying only one book a month.

"There's a library down the street," he said.

With the economy wobbling and people worried about job security and stretching their dollars, memberships at social finance sites such as Mint — which Hassenplug uses — and Wesabe.com have grown as people look for financial discipline.

The sites, which are free to join, are more than Facebook meets your checkbook. They offer forums where users discuss spending habits and solicit feedback from peers.

In addition, the sites employ interactive tools that help teach users how to budget and search for the best deals based on the spending habits of all users.

Useful spending patterns can be determined because the social finance sites are linked to a users' bank, brokerage and other accounts. Individual account data remains anonymous and secure.

Typical financial software is "good at telling you were your money went," said Wesabe CEO and founder Marc Hedlund. That's helpful, but it's not "good at getting you to a better place."

He said most people are uncomfortable talking about personal finance, even with close friends. But on a social site, where users have only a screen name, they are open and honest.

"People go into the discussion area and say, 'This is my situation, what should I do about it?' People can see they are not alone," Hedlund said, "and they can learn from others."

The interactive tools at Wesabe make specific suggestions on how to save.

For example, the site might suggest using a different auto mechanic, noting that other users have saved money using an independent repair shop. The site is able to provide specific store names because it bases its advice on aggregated payments culled anonymously from users' checking accounts.

Wesabe, launched in 2006, has more than 100,000 members across the country. The average user is a 28-year-old earning $50,000 to $60,000, Hedlund said. But over the last three months, as the depth of the nation's economic woes became more apparent, Wesabe has seen its biggest growth, with a 35 percent month-over-month increase in membership.

At Mint, the average user is 30 years old with an income of about $75,000, said Donna Wells, chief marketing officer.

Mint has been growing steadily since its launch in September 2007 — it has more than 475,000 users — but in the last month, "there's been a notable uptick in usage," Wells said. "People are looking for any new tool to help them budget and save."

Chicago media planner Ryan Rutledge, 24, uses Mint to track his 401(k) plan, his student loans, checking and savings accounts plus the balances on his five credit cards. He rents an apartment in a two-flat and is working on paying off more than $20,000 in student loans.

"It shocked me when I saw I was spending $500 eating out every month," he said.

He has cut back, to about $350 a month, and is working to lower that. The ability to track how much he spends and at what restaurants has helped rein in those expenses, he said.

"If I go over my budget for entertainment one month, I'll ask if I really needed something I bought," he said, looking over the data provided by Mint. "That prepares me for the next time I go to a store."

Rutledge is spending about the same each month, with one key difference: He's spending "at least $100 more a month" to pay off his debts.

Rutledge is reflective of Mint users overall. Each month since January they have reduced spending by 4 percent on gifts and charitable donations.

And they are treating themselves a little less, too.

"I went from spending $75 a month to less than $40 a month at iTunes," Rutledge said. But he admits to being an impulse buyer. He couldn't stop himself from buying the new Keane album at the online retailer.

"Of course you try to save money, but I really am spending more wisely," he said.