Beautifully variegated, it's been suggested it's a cultivar of Aloe arborescens called "Gold Rush", but what few pictures I've seen of that one are of a plant that's more heavily striped and lacks the spots mine has. Others have suggested a variegated Aloe saponaria. The photo above was taken right after I bought it. It was then about 16 inches across.
     It has since grown considerably and maintained it's variegation in both sun and partial shade. No offsets or flowers though. Below is a pic taken two years later. It's now over 24 inches across.