KeepCup is an interesting Australian company. As far as I can tell, they launched back in November 2009. The site describes KeepCup as a barista-standard reusable cup. It's made of "safe," recyclable non-toxic plastic, free of BPA and is avaiolable in 3 standard sizes and is available in many colors. The top has a unique, spill-proof design. The cups also have the potential to be branded and customized.
One of the neatest aspects of the web site, though, is their calculator. Simply plug in some info and find out how many cups, energy and landfill space you'll save be using a reusable cup. For instance, according to their calculations, if you buy coffee at a cafe three times a week and put it in a resuable cup, you will save 156 coffee cups, .4 kg of plastic lids, and 2 kg of energy per year.
You can buy selected colors here.