Google Inc. (GOOG) is enabling users to find and print coupons from merchants listed in the online search leader's index of local businesses, adding to a slew of free features designed to attract more traffic to its Web site.

More than 20,000 coupons are expected to be available Tuesday when the service debuts on Google's popular mapping service.

The initial coupon supply is being provided by Cox Enterprises Inc.'s Valpak Direct Marketing Systems, which has been mailing envelops stuffed with coupons and discount offers for nearly 40 years.

Valpak, based in Largo, Fla., plans to provide Google with nightly updates to expand the supply of coupons from a list of neighborhood merchants that will include pizzerias, auto shops, dry cleaners and handymen.

Google also is inviting businesses to submit their coupons directly to the search engine index. Links to the available discounts will automatically appear when Google's users are looking for local business information on the mapping service.

Yahoo Inc. (YHOO), the owner of the Web's second largest search engine, has enabled merchants to guide traffic to their coupons since 2004, said company spokeswoman Terra Malcom Carmichael.

Although Google isn't charging merchants or consumers, the coupon service could still help boost the company's rapidly rising profits by giving people another reason to use the search engine's own Web site instead of going elsewhere.

By expanding its audience, Google gets more opportunities to display the short, text-based ads that account for most of its revenue.

Although Google distributes the ads all over the Web, the company makes more money when people visit its site and click on the paid messages.

Within the next few months, Google plans to give advertisers the option of promoting a coupon offer — an alternative that would generate more revenue for the company.