I think all the dive shops in the Little Rock area either offer boat excursions or can direct you to shore sites for diving. I know Rick's does Lake Ouachita and Dive Shop II does excursions on Greers Ferry Lake in Heber Springs (north of LR). Poppa Smurph's in Sheridan does Lake Ouachita boat excursions and Dive Shop Billy in El Dorado does shore diving in Lake DeGray just west of Arkadelphia. All of the above lakes are US Corps of Engineer lakes where you can spearfish for gamefish.
Of the 3 lakes above, Lake Ouachita usually seems to have the best visibility since it is surrounded by national forest which helps reduce silt runoff.
In no particular order:
Rick's (NLR) - 800-521-three,five,four,one___Lake Ouachita
Dive Shop II (LR) - 501-666-three,four,eight,three___Greer's Ferry Lake
Poppa Smurph (SHER) - 870-942-five,six,seven,five___Lake Ouachita
Dive Shop Billy (ELD) - 870-864-zero,one,eight,five___DeGray Lake
As I mentioned before I'm sure any of the local dive shops either offer excursions or can answer your questions about shore diving on "their" lakes - I just know about these four personally.