I'll definately give K&D a big recommendation. I use one of their tuckable IWB and a belt, both of which are excellent quality and of the utmost comfort.
I'll add a few:
http://www.simplyrugged.com/ Great stuff, I absolutely love their ammo pouch.
http://www.highnoonholsters.com/index.html Great holsters readily available. Not the most ornate, but very functional for fair price with lots of styles.
Packin Heat is a great place to get Galco and Bianchi holsters, both companies are great for non-custom orders. I use one of each.
http://www.donhume.com/ I love the JIT Slide from here. Sturdy, durable, and cheap.
These are some I've looked into, but not used personally.
http://www.comp-tac.com/
http://rlcompanyusa.stores.yahoo.net/index.html
http://www.mernickleholsters.com/index.htm
http://www.epsaddlery.com/default.aspx
I've recently come across
DM Bullard and have been thinking about ordering a new holster from him. Haven't decided just yet if I "need" one.