I've had my Calamondin tree for at least 8 years now and it's so easy, pretty, and entertaining! I keep it outside in the spring/summer and inside in the fall/winter.
Easy:: It so hardy. It's taken a frost bite or 2, with no ill effects. It also went an entire summer outside without me watering it once. (for the record i just had the twins and i was busy!) And I'm pretty certain the boys pee in it. The thing just won't die.
Pretty:: I can't believe how this thing produces! It flowers 2 or 3 times each summer with pretty white flowers and just continues to give oranges. The oranges are comparable to the size of kumquats, but rounder. Look at this picture from 2009, christmas. (yes it's also our christmas tree) look at all those oranges! We didn't need ornaments that year.
Entertaining:: These things are so sour, we make lemonade out of them. I've also made lemon squares with them, use in tea, or throw them in smoothies.
Sometimes we just eat them for the "fun" of it! It's almost painful. These are real reactions after biting into the deliciousness...