I wear this daily. It is as comfortable sitting as standing. they have changed it since I bought this and the clips are now steel rather than the composite material. You can also get it with J hooks, belt loops and velcro.
+1 on the Desantis Tuck This II.
I use one of these daily with my 4" XD 40. Absolutely love it. I'm a very tall, thin dude (6' 3", 165-ish lbz) and it conceals well. Plus, for less than 40 bucks, I thought it was a great deal.