In reply to mypyrex:
Ahh Land Rovers... Putting oil back in the ground since 1948.
Check your cv joints, it could also be leaking from the differential too and running down the axle shaft. LR's are notorious for leaky diff seals.
After that its either the engine, gearbox or transfer, but I would imagine these are situated well away from where the slick is.
The colour of the oil might also be a tell. Transmission and drive-line oils are often coloured differently to engine oil. MTF94 (Gearbox) is normally red. EP80 (Differential) is gold/yellow. Engine oil is thinner and would be very very black. Of course the state of the oil will change with use.