If you've ever felt that twinge of regret the moment you hit the delete button on your digital camera, rest assured the image is probably recoverable--provided you use a tool like the $29 PhotoRescue Wizard. The utility scans the entire writable portion of your memory card and saves every recoverable byte of data to your hard drive. If there are photos on the card, it will probably be able to recover them.
Data recovery is an inexact science. Under normal circumstances, files that are "deleted" by cameras are not fully wiped from the card; the space occupied by those image files is just marked as available. If you take more pictures some or all of that freed-up space may be overwritten by new images, which will render the older, deleted images unrecoverable. So if you delete an image you want to recover, you will maximize the chance you can recover the image by immediately removing the card from the camera and not using it again until you use the data recovery software.
PhotoRescue can also restore images that are corrupted by the camera or some other device, such as a Geotagger gadget that mangles the photos' file header information. The Wizard's demo limitation is that it will only display thumbnails of recovered images. Once you purchase the product and get a license key, the program will restore the full image files to your hard drive or another storage device. But for those irreplaceable holiday snaps, less than thirty bucks might seem a bargain.