Lots of shopping (though mostly high-end stuff). CI is generally pretty expensive ($10 for a sub or a small DQ ice cream cup, for instance). If you're looking for inexpensive liquor or Cuban cigars (which I believe there's an executive order to legally allow to bring into the US -- consult your border control before you do) there are several good stores near the port; however, I found better pricing for both in Cozumel and Jamaica. I believe you can find a local semi-precious stone jewelry called Caymanite at good prices in some of the establishments near the port. Overall, though, having been to CI a few times, it really is all about the excursions -- even if it's just to the public beaches near by.