If you're a fan of the Smith & Wesson M&P series of handguns, Crimson Trace has a Lasergrip to help get you on target. The LG-660 attaches in seconds, replacing the backstop of the M&P, and is activated by a firm firing grip.
Crimson Trace's instinctive activation allows for immediate laser sighting with no additional motion necessary. Actuating the laser is as simple as acquiring a proper firing grip, literally. What differentiates the M&P Lasergrip from others is the placement of the button: while revolver and 1911 grips have the activation switch on the front of the grip, the M&P series places the button on the rear of the grip. It's a slight change, and not one that's noticeable when needed, but something to keep in mind when installing.
Crimson Trace sights in all lasers at 50 feet, which means minor adjustments may be needed depending on your preferred practice distance. Fortunately, a small allen key and detailed instructions are included with all Lasergrips, and within a few turns your Lasergrip can be adjusted to your specifications.