LoveSales - Find and save products you love, get alerted when they go on sale.
Domcomp - No-nonsense domain price comparisons, updated daily
TrackIf - Alerts you if the price of your favorite products drop
Savings.com - Compare prices at local stores & discover the best deals
Giftwhale - Giftwhale allows you to create personalised wish lists online.
PriceCute - Keep up with your competition's pricing on Amazon