Windows: While Windows 7 has built-in hotkeys to shift apps between monitors, Windows XP and Windows Vista do not. EasyMon adds in simple monitor switching to earlier versions of Windows.
In Windows 7 you can press WIN+SHIFT+Left/Right to move applications between monitors. For earlier versions of Windows with no hot key support for the task, EasyMon adds in simple application shifting. The default setting is WIN+Arrow Key, left/right move applications between monitors while up/down maximise and reduce the window size. The hotkey combination is customisable.
EasyMon is freeware, Windows only.