Pay per click and more
Every google search results page has some text advertisments in the right hand column. These ads are called pay per click, because every time someone clicks on one, the advertiser has to pay google $$$$. yahoo has a similar pay per click program. So how does it work?
Basically it's a keyword auction, you bid $$$ for trigger words that you are interested in. For example if you are in the jewelry business, you might decide to bid $1 for the word "necklace". Ads for businesses that bid more than $1 would appear above your ad, and ads for businesses that bid less than $1 would appear below your ad.
Typically, your ad links to a "landing page" on your site with some kind of special offer. Google provides extensive statistics about the effectiveness of your landing page offer and the effectiveness of your keyword selection. Pay per click works extremely well for small $$$ items like books and jewelery sold over the internet.
But what if you sell pizza? or your are a dentist or restaurant that serves a local area or does not lend itself to selling goods over the internet?
local.google.com and local.yahoo.com are free. When i searched for "pizza', local.yahoo.com returned 146 pizza shops within 10 miles of my zip code. When i googled "pizza near 19602", google returned more than 26,000 pizza shops arranged by distance from my house.
Explore both of these sites and make sure your business is registered. I've tried both and I like them both.
Did i mention they are free?