Since we're shifting into holiday shopping overdrive, sales, saving money, and spending seem to top our conversations virtually every day. So I must insist that you add the Retail Me Not extension to your Firefox browser.
It's going to help you do all three: save by alerting you when there is a sale or discount available, and help you spend less than you would if just browsing online stores till all hours of the night looking for a deal. It's free to add-on, but will be worth its weight in gold once you tally up your receipts at the end of the month and see how much you've saved.
And don't forget if you're looking for a bargain, you can always check out ShopStyle's Sale Habit, where you'll find tons of deals from all across the Internet!