Durham, NC - Python/Ruby/front-end/back-end
PlotWatt (<a href="http://plotwatt.com/" >http://plotwatt.com/</a>)  We've just completed a round of funding and are looking to expand the team and scale our product.  He have lots of interesting problems with large data sets, data visualization, game mechanics and user experience to name a few.  We're current a team of 4 so you'll be getting in early.
We're greentech, cleantech and eco-geeky.  We analyze smart meter data, pull out individual appliance usage patterns (without individual monitoring) and provide actionable advice to reduce energy costs and provide early warning on faulty/failing appliances.