There is a VERY attractive sport of this called Pesto Perpetuo (name's a bit too cute, in my book). I tripped over it at a garden shop, bought one, and then started to look it up (it having been nameless at the shop).
http://www.herbsociety.org/promplant/pestoperpetuo.php
BTW, if you want to keep one of these over the winter, the biggest hazard I've found is scale. Somehow, the plant looks clean when it comes in but the little critters have found it and make themselves at home.
Robin