I use ForeclosureRadar and like it very much. I have found certain trustee + lender combinations being the most motivated and have become pretty good at predicting opening prices for some of them. The issues really is about the postponments in foreclosures as to buying a specific property. Right now about 85% of trustee sales are being delayed. Some trustee + lender combination opening bid are at full market value only, others are at loan value. So it is would be useless to bid on those.
If you were doing investment where it is more about finding equity then these services are invaluable. For buying a specific property that is in the process.. It is a bit tougher. There are a lot of variables. But using the site, mining the data and learning the process will get you the best information possible in which to make your decision and that has some value.