If you use an Epson Scanner and Photoshop, you will want "One Touch Scan". This $10 shareware program lets you use the One-Touch button on an Epson scanner to automatically launch Photoshop and scan a document directly into Photoshop.
The program consists of a Photoshop Action and an AppleScript. When you push the One-Touch button on your scanner, the AppleScript tells Photoshop to run and execute the Action which activates the Epson twain software.
What do I Need?
AppleScript. 1.1 or later
Photoshop version 5 or later
Epson scanner with a One-Touch button (Epson 636 for example)