The Glock platform in itself is a marvel of gun design. Simple handling and function, great ergonomics and reliability across all demographics of use. There are also many options available on the market to consumers looking to expand the possibilities of a Glock pistol.
HI VIZ handgun sights
These handgun sights are affordable, and easy to install, though if you don't feel comfortable bolting them on any gunsmith or Glock armorer can install them for you. They offer a slightly lower profile, which means a lower height over bore ratio. The rear sight is not as effective at catching on gear for one handed manipulation of the weapon, but is still a viable option. In daylight the fiber optics really light up, giving a very clear sight picture. The rear and front dots are smaller and more precise than the factory white box and dot combination, offering more accurate shots over distance. In low light and dark settings they amplify the ambient light making them easier to pick up with your eye. There are many different colors available for these sights, giving you a variety plus the option to mix colors for easier front sight identification. Overall with an average cost of $100 for the sights and installation, they aren't a big bank buster for the economical substitute to tritium.
Glock magazine extensions
These are offered by Glock as an add on to standard magazines to increase their capacity. The 9mm magazine extensions offer an additional 2 rounds, giving a Glock 17 a 19+1 round count. They are simple to install, and utilize the same factory magazine spring, replacing the base and floor plate of the magazine. Feeding suffers no consequences, although when loaded to capacity the two rounds in the bottom tend to rattle a bit. There are also several different makes of Korean made Glock magazines, with slight differences between each one. The 33 round Korean mag pictured above for instance does not feed properly when a Glock OEM magazine spring is installed, but functions fine with the spring it comes with. Price range ~$10 per magazine.
Pearce Grip Frame Insert
This plastic plug inserts into the cavity of the frame on generation 1-3 Glocks, and fills the gap flush. It provides a beveled edge at the bottom of the magazine well which can be trained with to make for more positive mag changes. It is a snug fit, and will not fall out without a tool to pop the tab out. This model works on full frame models Gen. 1-3, and will not work on short frames. Price range ~$5
Glock Single Magazine Pouch
These ambidextrous mag pouches can be adjusted to fit different belt widths, and have rubber nubs within the pouch to retain the magazine. A solid pull will detach the mag. I was surprised at the physical flexibility of the plastic Glock used for these, but seem to be very impact resistant. They disappear under many shirts and jackets, and are not too noticeable on your side while say, driving a car, or any smaller space situations. The belt loops are on the center line of the pouch, so they can be loaded facing the front or rear of your body. Price range ~$9
Ghost, Inc. 3.5 lb Trigger and Springs Kit
This is a drop-in assembly kit to reduce the resistance on your trigger pull before the shot breaks. Once you understand the complete take down process for a Glock pistol, which you should regardless if you own one, installation of this kit is a breeze. There are videos available on Youtube for complete step-by-step disassembly, and you just swap in these parts in the factory parts' place. The kit includes a polished 3.5 lb connector, 4 lb firing pin spring, 6 lb trigger spring and a lighter firing pin safety spring. It is not recommended for self defense purposes, though adequate training should prevail no matter what the trigger pull is. Price range ~$17
Grip Force Adapter
The Grip Force Adapter is a great addition for those who have ever been ailed with the painful and bloody race tracks that can come with a high tang grip on an auto pistol. The beaver tail gives plenty of buffer room for the webbing of the hand, allowing a high grip while keeping space from the moving slide. At a $20 cost, the kit came with 2 different adapters actually, one smooth and one with a more aggressive grip, letting the user choose which fits their hand better. Or just keep the one that fits and sell the other! It installs easily, and comes with the pins needed for replacement. All one needs to do is simply pop out the trigger housing pin on the back of the grip (for Gen 1-3 pistols, there is a separate part for Gen 4s), slip in the longer replacement pins, and rock the grip into place until it snaps. It can be installed without any field stripping or dis-assembly, but it may be safer to at least field strip the pistol, just to err on the side of caution.
In the end, you should aim to use what works for you 95% of the time. There are countless options and accessories available today that you can't quite understand the operation of until you try them for yourself. If anyone else has had successes or failures with these or other Glock parts and accessories we would love to hear them! Be safe, and have fun. Here are some photos of 7 yard shots taken with this configuration of parts and add-ons.