DryFireMag is a modified Glock magazine that allows you to practice dry firing your Glock safely at home. Typically to practice dry firing your Glock it involves a lot of repetitve racking of the slide to reset the trigger, or a lot of imagination.
Enter the DryFireMag. You make sure the chamber is clear and no ammo is in the Glock. Insert the DryFireMag and when you press the trigger you get a tactile sensation that mimics the feel of a Glock trigger and the audible clicking noise.
In this video by DryFireMag, you can even use their DryFireMag in conjunction with a Laserlyte laser.
The DryFireMag is a bit pricey at $100 but it seems to work very well and if you like to practice dry firing at home, this may be the training aid you have been craving for. For more information check them out at http://www.dryfiremag.com/