Dive Rite makes a thigh pocket that has a loop you thread the waist harness through. I had one, but unfortunately the ACB weight pockets get in the road. Halcyon also make harness pockets that attach to the backplate, similar to a ACB weight pocket. I think Fifth Dimension have a thigh pocket of their own design that you can strap to your leg with bungee cord.
Of course, you have to ask yourself, will you need pockets? If you're just doing rec diving, you might be able to get away with using the D rings on your harness. I stow a safety sausage on my rear D ring, spare light clipped and bungeed on the chest harness, and rarely carry anything else that you could conceive to put into a pocket. If I do a night dive, I clip a strobelight to my rear crotchstrap D ring as well (not turned on, just for surface use). But if the diving you are doing calls for carrying some reels, slates, tables, etc, try one of the above options. No doubt other manufacturers like OMS have harness pockets as well.