Walgreens recently expanded their online rebate submission area. If you live in Alabama, Arizona, Georgia, Hawaii, Massachusetts, Minnesota, Tennessee, or Wisconsin, you're in luck.
While I've not done it myself (I can't wait till they include my state!), I've heard from those who have done it that it much simpler and easier than the mail-in rebates. You enter receipt information on their website, the system approves your submission, and your gift card is usually reloaded in a matter of days. (Sounds far better than the weeks or months it sometimes takes by mail!)
And if nothing else can pique your interest, remember that you're saving a stamp every time you use online submission. :-p
For more information on the rebate program, click here.