In Adobe Photoshop CS5.5 / CS6, is there a keyboard shortcut to make a new frame using the animation window and timeline?
I make a lot of gif animations and would like to reduce mouse movement for productivity.
No. But, you can make a hotkey for it.
From top menu: Edit > Keyboard Shortcuts.. ( Ctrl+Alt+Shift+K )
Just select Palette menus from the drop down list and then Animations. Once you've given a hotkey press Accept.
( Make sure to listen to photoshop when it warns you if the inserted hotkey combination would override any existing ones. You can try to use Ctrl, Shift and Alt to make sure that it doesn't happen. )