With more than $31 billion in online sales for a single quarter in 2007, it's easy to miss out on a hot online bargain without a little help [source: U.S. Census Bureau]. And, pricing alerts are a great way to stay on top of those bargains.

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Retail giant Wal-Mart will send an alert by e-mail or text message when an item of interest to you goes on sale.
To receive pricing alerts, most online retailers allow you to complete a form with your e-mail address if you want an e-mail alert, or your cell-phone number if you want a text message. Retailers will send you alerts or automated notifications when the price drops on an item you've previously purchased, or when they're holding a special one-day sale. They may also e-mail you specific offers such as free shipping with $100 purchase.

These alerts aren't just for finding bargains in the usual places. Did you know you can also use online pricing alerts to keep up with real estate and investment options? For instance, you can beat a fellow house-hunter to making an offer on your dream house. Or, you can get advance notice on how your favorite stocks are doing in the market.

In this article, we'll examine the different types of pricing alerts: one for investment prices, another for real estate deals and a third online shopping.