If you need to resize a bunch of pictures (for example, before publishing them on the web), it is a pain in the neck to collect them all and play with the Photoshop commands. For Windows users, here is a utility program that does exactly this in a nice way: All files of a directory, with a lot of neat options.
Resize My Photos is freeware, for Windows. It even has a cool right-click menu for Windows Explorer integration.
Worth trying.