UltraMon is a must have application for anybody using multiple monitors! My favorite feature is having a taskbar on each of monitors. That way everything being displayed on monitor #2 is not filling the taskbar on my main monitor.

Quoted from the developer:

UltraMon is a utility for multi-monitor systems, designed to increase productivity and unlock the full potential of multiple monitors.

• efficiently move windows and maximize windows across the desktop
• manage more applications with the Smart Taskbar
• control application positioning with UltraMon Shortcuts
• multi-monitor support for desktop wallpapers and screen savers
• mirror your main monitor to secondary monitors for a presentation