Google Adwords has been running a special internet marketing promotion since before the holidays. A free $100 matching credit for bidding on Adwords keywords.

But it ends tonight, according to their site. The promotion is available to new users that sign up for Adwords, and existing users that set up a conversion tracking tool, before January 15, 2011.

Adwords are the ads you see along the top and right hand side of a Google search page when you search for something. The ads also show up on many websites, like ours (see above ads).

The order in which Adwords ads are ranked is based, in part, on how much money the advertiser has bid to pay for each click thru that the advertisement receives. Google also applies a quality score to each advertisement, which is figured into the ranking order.

Google promotes Adwords as a cost effective means of internet marketing. Ads are displayed for free, and the advertiser is only charged when someone clicks on the ad to visit the advertisers site. Google also offers an Adwords Keyword tool, with an estimator of the traffic that can be generated, geared toward helping advertisers select the keywords they wish their ad to show up for.

New Adwords advertisers who sign up by tonight can receive a $100 matching credit if they spend $100 on Adwords advertising by February 15.

Existing users can qualify for $100 in matching funds if they set up conversion tracking by tonight and spend $100 on Adwords by February 15.

These Adwords specials are limited to businesses in the U.S and Canada (please see their site for additional restrictions), and users must sign up at: to qualify.