Gift Hero - The best wish list ever
LoveSales - Find and save products you love, get alerted when they go on sale.
GiftBuster - Wish list registry & shopping list app
TrackIf - Alerts you if the price of your favorite products drop
Giftwhale - Giftwhale allows you to create personalised wish lists online.
Mystery Gift Bot - Don't think about what to buy, let it be a mystery