BetterTouchTool allows you to set a trigger to move a window to a second monitor, such as the one below:
Trigger: Doubleclick Window Titlebar; Predifined Action: Move Window to Next Monitor
Alternatively, a mouse button, keyboard shortcut, Apple Remote, Magic Mouse or trackpad gesture could be set up as the trigger.
Slate is an extremely customisable tool that allows you to set window layouts/positions through keyboard shortcuts. Combining this with a BTT gesture, you can create a gesture-driven window movement tool for free!
Slate is a window management application similar to Divvy and SizeUp (except better and free!). Originally written to replace them due to some limitations in how each work, it attempts to overcome them by simply being extremely configurable. As a result, it may be a bit daunting to get configured, but once it is done, the benefit is huge.