Want to reach consumers in the growing online coupon market? Below are five of the Web’s most popular online coupons sites (although there are several more), ranked in order of unique monthly website traffic, according to Compete.com data as of December, 2009.

Coupons.com (14.6 million): Far and away the most visited coupon website. In 2009, $300 million worth of coupons were printed and that number is expected to triple by the end of next year.

RetailMeNot.com (9.9 million): From modest beginnings, RetailMeNot has nearly doubled in usage since late 2008.

CouponCabin.com (3.4 million): CouponCabin features discounts available online, printable coupons and localized offerings. They also (along with Coupons.com) offer an iPhone app for even greater exposure for merchants.

FatWallet.com (2.1 million): One of the industry’s pioneers, FatWallet.com started in 1999 and includes more than 800 merchants.

DealCatcher.com (1.3 million): While not the largest coupon site out there, DealCatcher does a good job highlighting techoriented and consumer products, along with a recently released grocery section.