In addition to the Beretta and other .25's mentioned already, there's the Kel-Tec P32, which as the name implies is a .32 caliber (bigger/more impact than a .25).
http://www.alpharubicon.com/leo/keltec32stryder.htm
That being said, it's hard for me to imagine anyone (with the possible exception of a COMPLETE MORON) carrying a gun in their front pants pocket, especially such a small gun. Two simple reasons:
(1) you really don't want your gun moving around (what if the pocket's fabric catches on the trigger?! What if the gun turns so it's pointed in a very undesirable direction, such as straight at your crotch?!), and
(2) you want to be able to grab your gun immediately, rather than having to dig in your pocket for it.
You can fix problem #1 by putting the gun in a tiny holster and putting the whole shebang into your pocket, but that doesn't fix problem #2.
The link above shows a couple of options for carrying it, and here's another one--this one is probably the most common way to carry small guns, and it's also the most similar to carrying it in your pocket, so perhaps it's the best for your story:
http://boldt.us/PAGOA/KELTEC_P32_BELT_CLIP.JPG
The gun is in a very small holster that has a clip that holds it to the waistband of the pants. If you really need it to be in the character's pocket, the same holster could be used there: put gun in holster, put holster in pocket and clip it around the top of the pocket. The clip would be more visible than when it's at the waistband (you can always cover a waist-level clip with a belt), but problems #1 and #2 above would be solved. However, keep in mind that the other reason most people carry on the waistband rather than in the pocket is that it's easier to sit down when the gun's at your waist. When it's in your pocket, it's much more likely to get in the way and need adjustment when you sit down.