I second super midget for packing.org. THey are a great resource, especially the ccw database.
Did you mean SOB (Small of Back) carry? because that is generally considered a bad idea. Instead, you will probably have the most luck carrying over one of your kidneys (basically between your hip and your spine). SOB carry is generally discouraged because if you fall on your back, the gun can snap your spine, paralyzing you. It is also pretty hard to draw when the gun is all the way behind you.
I highly recommend a FIST K1 Universal holster setup for IWB carry (Inside Waist Band).
http://www.fist-inc.com/holsters/k1/Default.htm
(it's the first holster on that page)
I use one of these, and it is the best holster I have ever had (and I have gone through a bunch, both cheap and expensive).
Most cheap holsters are bulky...which makes concealing your weapon more difficult, and clunky.
FIST holsters are made to order, and it will be specially molded to fit your weapon (they use their own glock-19's, so you don't have to send yours in). They are very low profile, and very comfortable. Mine is very positive, the gun stays put, even when I am running or horsing around, but when I want to draw, the weapon comes out very quickly.
Since they are made out of kydex, it will protect your weapon from sweat/moisture, which is a big deal when you are carrying your weapon every day.
IWB is important for me because it gives you a little extra wiggle room by better concealing the weapon. The majority of the weapon goes inside your pants, and is not visible if your shirt gets pulled up. Also, since it is inside your pantline, it is pulled closer to your body, and the weapon will 'print' less. It is very comfortable, so long as you wear underwear or an undershirt between you and the gun.
Leather holsters can be very good, and I have an expensive one (Galco Concealment (another good holster)), but it just doesn't work as well as my fist.
You might want to purchase a cheap holster so that you can try carrying and figure out what features you want in a holster. Then you can go get a nicer one that has the features you want.
Some important things to mention:
just about any holster will hide a weapon if you are standing up and not moving (with a shirt over it, of course). However, problems arise when you have to start going about your daily routine. I.e. reaching for boxes, hugging people, leaning over, sitting (big one), twisting, getting caught in the wind, wearing wet/sweaty clothes, etc. Bear this in mind when you pick a holster.
Anyway, good luck.