Please don't fall victim to the foreclosure traps the Internet provides. All foreclosures are listed in the MLS. After all, what seller wants to keep their property separated from the buying public? The online sites that try to sell you foreclosure listings and/or information are just trying to separate you from your money. A good buyers agent can make sure you see all the homes available for sale.
Carlo makes a good point about foreclosures though. Many are sold before they become available - people had inside information about when the home would be coming on the market and make their offer the same day. There's no web site that can predict listings like these. You must do some research yourself or have an agent that has access to real estate owned properties do it for you.
This assumes that getting the absolute best bargain is the most important thing to you. Most buyers want a great home at a great price. You can waste a ton of time trying to get the "best deal". If you focus on foreclosures only you miss other opportunities that may be available. If you'd like examples contact me directly.
I would like to invite you to visit my site http://www.MyHomeComps.com where you can search for foreclosures, save your searches, and get alerted as new properties become available.
Don't do it. I don't get why Trulia would partner with realtytrac. It wasn't to help us searching for houses, it was so trulia could gain money. Cmon, no corporation does anything for the people without some gain. Well, generally.
I suggest working through a Buyers Agent (signing a contract). In Michigan, agents can only work for the home buyer under such a contract. It can be for one home, one day, a week, or any period of time you're comfortable. Most foreclosures take several months to close.
http://www.MIforeclosureDeals.com is a site dedicated specifically to foreclosures in Southeastern Michigan. There is no cost for the lists of foreclosures and the site offers some good advice to anyone interested in purchasing a foreclosure.
Be sure (IF you are serious) to have your financing in line an acquisition strategy in place. While there are many foreclosures out there, in many cases the good ones are selling FAST.