When Robert Shockey is searching for sales prospects, he turns to the Internet. The CEO of Great Outdoor Network Inc., a West Palm Beach, Fla., outdoor advertising agency, relies on sites such as Jigsaw.com to help him identify and get contact information for the marketing executives who are the 4-year-old company's best customers. "We do a lot of combing of the Internet," says Shockey. "We use sites like Jigsaw to pull the right people and get to the marketing vice presidents so we can expose them to the power of out-of-home advertising."

Many other small business owners are finding online tools for sales prospecting both effective and inexpensive. Options range from sites devoted specifically to sales prospecting to general-purpose search engines such as Google and even social-themed services like MySpace. "There are so many of these networking sites that you can really take advantage of them," says Gary Chen, senior analyst at technology market research firm Yankee Group in Boston.

One of the main players in the space is Jigsaw, an online directory with e-mail, phone and other information on more than six million people. In order to access the service, users can either add 25 new contacts each month from their own contacts databases, or pay $25 per month. Subscribers also get credits for correcting incorrect entries, and may lose credits for posting incorrect ones.

Prospecting service Spoke has data on more than 35 million people at 900,000 businesses. Some data is user-contributed; the rest is gathered from online and offline public sources. Profiles may include name, title, phone, address, job history but not direct e-mail address unless the profilee okays it. Instead, Spoke describes the e-mail address patterns used by a person's employer so that prospectors can figure out the e-mail of someone they'd like to contact. The basic service is free. For $50 a month users can get more data and management tools.

Plaxo is an online address book that more than 15 million people use to store and access their contact databases from any place with an Internet connection. For sales prospectors, its most relevant feature is that whenever anyone updates a contact with new information, other Plaxo users who have that contact in their address books receive notice of the update. That can help ensure that your contacts are up to date. The basic service is free. For $50 a year, users get extra features such as automatic synchronization with LinkedIn contacts.

ZoomInfo.com is a business search engine with information on nearly 37 million people and 3.5 million companies. The free version of the service lets you search for people by name only, or you can search on more than 20 variables by paying a subscription to use ZoomInfo Powersearch.

While the Internet is a significant addition to the sales prospecting toolkit, it does have limitations. For instance, Shockey says outdated or incorrect data can be a problem with some services. An even bigger issue, for him, is that prospects whose contact information gets into one of the services can be bombarded with sales calls, prompting them to change or delete their profiles. "It takes good contacts and flushes them out of the system when they change their information," he says. Shockey would prefer an opt-in approach such as the one employed by LinkedIn, where people are alerted that someone is asking them to join a network, and they can choose to do it or not.

Online sales prospecting has been growing by giant leaps lately, as businesses' need to contact good potential clients intersects with the connective power of the Internet. It's one of the most attractive of the many online marketing tools that entrepreneurs have available to them, says Chen. "This stuff is definitely a great way for small businesses to get leads," he says, "and make more sales."

Mark Henricks is a freelance writer based in Austin, Texas.