Finding Valuable Coupons Online (and Coupon Codes)

The Internet is such an incredible resource for all Frugalites. It makes research and comparative shopping a breeze...and it is an invaluable way to find high value coupons, and even Free Product Coupons! How do I find these coupons, and valuable coupon codes? Here are a few ways I've found coupons online:

1. eBay - Free product coupons are sometimes sold on eBay. If you can find a lot of coupons that are a bargain - and allow you to get some very inexpensive groceries to fill the pantry! - it might be well worth it to buy a lot or two of coupons from eBay. This is also a way to find coupons you might never find otherwise. You can also find free product coupons and high value coupons this way...sometimes with those high value coupons, the product is nearly free after the coupon is redeemed.
2. Google - Get savvy with searching for coupons with Google! Try searching for exactly what you're looking for. For example, if you're looking for peanut butter coupons, search the brand name, plus the term coupon, like this: "Jiffy peanut butter +coupon." Or, try searching for printable coupons online from your favorite retailers or grocery stores.
3. Finding Coupon Codes - Coupon codes aren't a physical paper coupon, but rather a valuable code that can be applied at checkout to your online purchases. Sometimes these can be an incredible bargain! I've had online coupon codes for Sears and other online retailers that saved me $20 or more on a $100 purchase! Again, use Google or your favorite search engine and use search terms like: "Sears +coupon code" or "Amazon +coupon codes"

Have any more online coupon hunting techniques? Please post a comment with your ideas!