I'm biased (since I work there), but if you're looking for a comprehensive foreclosure listing database, you won't find a better one anywhere than RealtyTrac. We collect data directly from public records in the county courthouses in over 2,200 counties (94% of U.S. households) and update the database twice daily. In addition to breaking out the listings by type (in FL, that's Lis Pendens, Notice of Foreclosure Sale and REO), we add property characteristic data (beds, baths, etc.), comparable sales, estimated market value, loan history, owner contact information and aerial or street level photography of the properties. We currently have over 1.5 million properties in the database, which is as current as the public records that we source (so yes, there is occasionally some lag time between when a transaction happens and when local records get re-posted). But it's a great source to use in conjunction with your local MLS.
Keep in mind that MLS rules vary pretty widely when it comes to foreclosure property listings: some require properties to be noted as bank-owned, some forbid it. Most don't note properties that are in the early stages of foreclosure (Susan's note below is a good case in point - short sale properties are almost always in foreclosure, but may not be noted as such on the local MLS).
You're in a state where some counties do post the Lis Pendens (initial notices of default) filings online. If your county does this, it should be a free service. You may also want to research which law firms handle most of the foreclosure activity in the state (for a directory of firms, go to http://www.usfn.org
); sometimes these firms have free websites listing upcoming auctions. The trade-off for "free" vs. "paid" sites is usually money vs. convenience. Only you can decide which is best for you.
If you're interested, we do free monthly "Foreclosure 101" webinars for agents and brokers who are trying to gain more expertise in the foreclosure market. You're welcome to sit in on one, if you'd like. Feel free to e-mail me and I'll get you on the list - email@example.com