Michael sent me this Tuckable IWB holster for the Smith & Wesson M&P9 compact. It's supremely well-made, with double stitching in critical junctures. The holster is "rough out" construction, so that the interior is smooth and precisely molded to the M&P, but with sufficient "rough" outside to help hold the holster steady inside the waistband. Sturdy metal belt clips located on the outside edges also keep it in place, as well as helping distribute the weight evenly over the belt.
It's eminently tuckable, as well - with the clips placed under a belt and a shirt tucked over the holstered firearm, the entire rig just disappears under clothing. Only the very bottom of the clips are visible, and unless you know exactly what to look for and where to look, even concealed carriers have trouble spotting the holster's presence.
MSRP starting at $200, with a variety of custom options available.