I'm a huge fan of classic H-P calculators, especially the HP-16C -- their first and only programmer's calculator. It has become a much sought-after collector's item, which ensures that good examples sell for insane amounts on eBay. That's not so great for those of us who actually want a real, honest-to-goodness programmer's calculator on our desks.
Enter DM Swiss Made Calculators. These clever little Swiss devices are miniature emulations of vintage Hewlett-Packard calculators, including the HP-11C (Advanced Scientific Programmable), HP-12C (Business Calculator), HP-15C (Scientific with Matrix & Complex Math) and HP-16C ("Computer Scientist" model). Each model costs 89 Swiss Francs (about $95) and is available in untreated, brown and blue titanium. They run on a single CR2032 battery which should last for years in normal use, and it's possible to update the firmware using a serial connection.
Apart from that... they're calculators. They're really small. They fit in cool leather pouches, too.