This JavaScript (Invert Foreground Color) inverts the foreground color in Photoshop.
To install:
1) Download and unzip the file
2) Quit Photoshop
3) Place the script in your Photoshop CS3/Presets/Scripts folder.
4) Launch Photoshop
5) Select a foreground color
6) Choose File > Script > invertForeGroundClor
Of course you can assign a keyboard shortcut to the script by selecting Edit > Keyboard Shortcuts, selecting Shortcuts For Application Menus and scrolling down to File… Scripts… InvertForeGroundClor

This reminds me… Will we ever be able to assign keyboard shortcuts in LightRoom? Like, maybe, LR 4? Please?
Hi Ron, Thats a great suggestion that I’ve heard several times. I would strongly encourage you to also request it on the Adobe Lightroom Forums: http://bit.ly/98NlBq