How to control Windows 7 snap feature with two monitors?

"You should use only keyboard shortcuts for that configuration, since mouse movements alone seems not supported for that special side that crosses over to the other monitor.

NOTE: On multiple monitors, continually pressing a keyboard shortcut combination below will cause the window to snap to the side and scroll in that direction through the multiple monitor screens.


Windows Key + ←
This will snap the current window to the left side of the screen, or unsnap a window that is snapped to the right side of the screen.
Windows Key + →
This will snap the current window to the right side of the screen, or unsnap a window that is snapped to the left side of the screen."

"If you don't want to use Keyboard shortcuts (Windows Key + Arrow Left/Right) and/or you want to be more flexible (e.g. 4 windows per screen), there are two options to Snap-Resize through your mouse:

AquaSnap ($9,- $14,- per user)

http://www.nurgo-software.com/products/aquasnap

Cons:

no delay crossing if you move a window between two monitors (so you need to move very slow to target the correct one)

Since 2014 all these cons are not present anymore:

it lacks the feature to disable the restoring of a window size after it is moved again
I've mailed the developer some suggestions (02/2013), he answered fast and promised to realize them, but the project seems to be dead.
a maximised window can't be moved (the windows 7 built-in feature is able to do that)
does not support keyboard shortcuts

and

WindowSpace ($24,95 per user)

http://www.ntwind.com/software/windowspace.html

Cons:

the preview frame is under the moved window, sometimes the window is bigger, so you don't know if the window will be half or quarter size of the screen (not a huge issue)
no delay crossing if you move a window between two monitors (so you need to move very slow to target the correct one)
I've contacted the developer as well (23.11.2013), but I didn't get an answer by now.
a maximised window can only be moved if the ""restore old size"" option is enabled

General

It is possible to get the delay crossing of multiple monitors through Dual Display Mouse Manager:
http://ddmm.sourceforge.net/

But this app has some bugs:

problems if you switch on a monitor after windows has been started
problems if you wake up the pc
it is to complicate to use Ctrl + ~ with a non english keyboard to bypass the delay crossing (and it is not possible to overwrite the hotkey)

As you see there is no perfectly working app available. At the moment I hope WindowSpace will solve this problems as it seems to be the most active project. After that it will be perfect, but of course, expensive."

If you have a docked toolbar on the inner seam of a multi-monitor setup then you will be able to use the half-monitor snap feature on that monitor when you hover over the toolbar. I use Trillian Astra Instant Message program with the right dock setting and am able to snap to half the screen when I hover over the toolbar. If you had two toolbars, one on each side of the seam then you would be able to use the snap feature on both sides of both monitors. See this question for more info.
If you have a docked toolbar on the inner seam of a multi-monitor setup then you will be able to use the half-monitor snap feature on that monitor when you hover over the toolbar. I use Trillian Astra Instant Message program with the right dock setting and am able to snap to half the screen when I hover over the toolbar. If you had two toolbars, one on each side of the seam then you would be able to use the snap feature on both sides of both monitors. See this question for more info.