Google Checkout will now be free to use for all online merchants through the end of 2007, regardless of whether they are Google AdWords advertisers.The no-fee promotion, originally slated to end Dec. 31 of this year, was extended through the end of 2007 based on positive response from merchants, Internet Retailer writes. The standard fee for using Google Checkout is 2 percent of the sale plus 20 cents per transaction, and retailers that use Google Checkout and are also AdWords advertisers can process $10 in sales at no charge for every $1 they spend on AdWords. But during the promotion, merchants will receive free processing regardless of how much they spend on AdWords.

Google Checkout is also giving those with merchant accounts the ability to create coupons at Google Checkout’s merchant center. Merchants can specify dollars- or percent-off coupons and add restrictions.

Retailers can also bill customers for purchases by sending them a Google Checkout invoice via email, which will include a link that customers can click to pay via Google Checkout.