Sure, your company's website brings in business, but it can also become a revenue generator in its own right. Using these free services, you paste a little code into your website and pick up revenue when people stop by. It's easy money, but proceed cautiously. For one thing, customers could be turned off by a site that's cluttered with ads. Plus, ads typically steer visitors away from your site, which is particularly worrisome if you've inadvertently displayed ads for your competition. These tools aren't right for every business, but handled with care, they could pad your profit margins--or at least subsidize your Web hosting fees.

Best For: Making money with little effort

What it does: Displays text, image, and video ads based on your site's content

What's cool: Google (NASDAQ:GOOG) searches your site and serves ads that are relevant to its content. Its smart technology and huge pool of advertisers typically translate into above-average payouts. Once you've been approved as a publisher, any site you run can use Google AdSense. You can block competitors from advertising on your site by blacklisting their websites.

Drawbacks: It doesn't let you approve ads before they run on your site. In fact, because Google's ads are based on your site's content, there's a good chance the ads will tout goods or services that compete with yours.

What it pays: Typically from 5 cents to $15 a click, depending on the content in the ad.

Best For: Selling ads to your customers

What it does: Serves up a wide variety of advertisements, including text ads, banner ads, and interstitials--ads that briefly take over an entire page of your website

What's cool: AdBrite lets you approve or ban specific ads before they appear on your site. Plus, you can place a "Your Ad Here" button on your site that allows visitors to buy an ad in that slot. So if your company makes, say, business software, your customers could advertise to one another on your site.

Drawbacks: Interstitial ads could annoy your visitors. Also, you'll have to spend a few minutes a day approving or banning new ads if you want total control over what will appear on your site.

What it pays: Depending on your traffic and the type of ad, expect to earn 10 cents to $10 per 1,000 views.

Best For: Keeping rivals at bay

What it does: Delivers ads that feature random items being auctioned on eBay (NASDAQ:EBAY)

What's cool: If you don't compete with eBay sellers, there's little chance of undercutting your own sales. With AuctionAds (which is not affiliated with eBay), you get a commission if a visitor from your site ends up buying what the ad is touting. AuctionAds lets you set keywords--like DVDs or automobiles--so you get ads only for items fitting that description. You can also specify that only eBay items in a certain price range get shown in the ads.

Drawbacks: You get paid only if visitors buy something on eBay after clicking on your ad (unless they sign up for eBay--see below).

What It pays: You get about half of the fee sellers shell out to eBay, which is typically from 3 percent to 4 percent of the sale price. You can also collect about $25 if someone who clicks on your ad registers for the first time at eBay and bids on an auction within 30 days.

Best For: Promoting ancillary products

What It Does: Serves up image ads that hawk consumer products. Each ad contains up to four products as well as a short description, pricing, and links to retailers.

What's cool: The ads are relatively slick, and you get to decide what sorts of things are in them by choosing from 45 categories of stuff. A travel agency, for example, could promote products--such as digital cameras and camcorders--that its customers could use on their trips. The ads are available in 15 sizes.

Drawbacks: If you make or sell products, especially electronics, the items in Chitika's ads might compete with yours. And the ads allow visitors to preview information about the products without clicking on the ad.

What it pays: From 20 cents to $2 per click, depending on the product

Best For: Keeping visitors on your site

What it does: Conducts market research by placing polls on websites. You get paid when visitors see a poll on your site.

What's cool: You control the look of the polls and can customize them to fit into your site's design. Plus, you can designate different polls for different parts of your site. The poll questions aren't controversial, because they are related to market research, but if you object to the content in a poll, Vizu will remove it immediately. Best of all, poll takers never leave your site while they are answering questions.

Drawbacks: Research demand drives the placement of polls. Only sites with desirable demographics and a high participation rate will get the top fees.

What it pays: For every 1,000 people who view the poll on your site, you get from 50 cents to $10.

Best For: Displaying banner ads

What it does: Offers banner ads from national advertisers

What's cool: ValueClick has one of the largest pools of marketers and serves up ads for well-known brands, such as Netflix (NASDAQ:NFLX) and eBay, that probably don't compete with your company. You can also approve or ban specific ads to control exactly what appears on your site. ValueClick also offers a separate service called Commission Junction, which pays small commissions every time clicks from your ads lead to a certain action, such as a purchase or filling out a form.

Drawbacks: The banner ads often feature video and other flashing graphics, which may distract visitors or tarnish your site's design.

What it pays: From 25 cents to $2 for every 1,000 people who see the ads

For mor tips on Web advertising and doing business online, check out