DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
Preme for Windows - Speeds up your window switching.
WindowGrid - Quickly and easily layout windows on a dynamic grid using just the mouse.
GridMove - GridMove - A window management tool that can quickly arrange your windows into desktop grids.
Mizage Divvy - Divvy is an entirely new way of managing your workspace.
Ultramon - UltraMon is a piece of software built to help with the management of multiple screens on the same computer system. Without software like this, taking full advantage of an expanded desktop space can be difficult.