Ultramon

Ever since i first setup a pc with multiple monitors i've been frustrated with how windows handles it.  It's like nobody put any thought into it.  That's where Ultramon steps in.  Ultramon (http://www.ultramon.com/) is built to specifically handle multiple monitors.  There are two main features I use: smart taskbar and window switching.

• Smart Taskbar: ultramon puts an additional task bar at the bottom of each monitor.  The windows in that monitor only display on the task bar of that monitor.  This means that a window on your secondary monitor shows up in the task bar of the secondary monitor (not the first).  This feature works fine in windows7, but diminishes some of the new task bar features in windows 7.  It works wonderfully in XP.
• Window switching: this feature is particularly handy because i have a mouse with a few extra programmable buttons.  This feature allows you to move the current window to the other monitor.  Much easier than dragging the window from one to the other.  I take this two steps further by first going into the UltraMon config and setting a keyboard shortcut that move the current window to the next monitor.  Then i go into my mouse settings and set one of my buttons to map to that keystroke.  This means that when i hit that button on my mouse, the keyboard shortcut gets virtually pressed and UltraMon moves the current window to the other monitor.

This feature isn't so useful in Windows 7 because the snap feature is a little sexier.  With snap, i can hold the windows key and press the left or right button on the keyboard.  This snaps the current window to the left or right side of the current monitor.  Repeating that keystroke sends it to the left or right side of the other monitor.  Keep repeating the process and the window gets snapped in a sequence to 3 positions on each monitor.  I map that key stroke to a button on my mouse and i get the same functionality as with UltraMon.
The full version is worth it, but you can try it out for free first.