Are you talking about the port in the lower-center dash (below the HVAC controls) that looks like a cigarette lighter plug? If so, just about anything that is 120 watts or less per the owners manual, but also not a cigarette lighter itself. I used mine to power a dash cam.
Blue Ocean 2012 Leaf SV, lost that 1st bar on 11/21/2015 at 26,435 miles.
Lease returned on 12/23/2015. Final LeafStat figures: 225 Gids, 17.44 kWH, SOC 91.89%, SOH 82.36%, 69.49% HX, 54.57 Ahr, battery temp 61.8 F
Now driving a 2015 VW eGolf SEL