Mint.com, a free Web site that helps people manage their money, launched a year and a half ago, and already has 900,000 users. The company is building its following by giving customers what they want. When the site launched, users could track their checking, savings and credit card accounts. Before founder Aaron Patzer made his next move, he surveyed his clients. They wanted investment and loan services, so Mint.com added tools to help them monitor the performance of their portfolios and the interest rates on their loans. Forty percent of them owned iPhones, prompting the company to roll out a special application for the device. In these tough economic times, it's crucial that small businesses stay attuned to their clients' needs. Companies that fail to do that will be in the market for a "going out of business" sign. To stay out of the red, follow these rules: Set goals: Before you talk to customers, identify what you want to learn. At the least, you should aim to find out your clients' service expectations so you can evaluate how well you meet them. Managing those assumptions is an important part of customer satisfaction, says Kesi Stribling, chief executive officer of KSG Strategic Consulting. Survey away: People don't have time for a 10-page questionnaire, so keep it short and simple. Janine Popick, CEO of VerticalResponse, which distributes surveys on behalf of other companies, says that surveys should offer an area for respondents to make suggestions. Get it online: The Internet has made it cheaper to probe your customers' minds. For $15 a month, Constant Contact helps users create surveys, track responses and follow-up with clients. Zoomerang offers a similar service for $19 a month. FreeOnlineSurveys.com is free, but surveys are limited to 20 questions and 50 respondents.