In my experience, revolvers make the ideal pocket guns because they can offer a cartridge of respectable power in a package compact enough to fit in a pocket with rounded contours that don't print as noticeably. Colt D-Frames are nice in that they hold six shots, but the slightly smaller S&W J-Frames seem to fit most pockets more easily.
Colt Cobra .38 Special
S&W Model 36 .38 Special