I've been loving a Swrve mid-weight hoodie I got on closeout a few months ago (the link is to the current updated new/improved model):

http://www.swrvestore.com/servlet/Detail?no=104

I have worn it almost every day since I got it: with just a t-shirt it is good down to the low 50's. For 30-40 degree weather I add another insulating layer - either a Mont Bell Ultralight Thermalwrap or Ultralight vest. It is windproof and can pass as casual wear. The new model has pit zips which I wish mine had. It is lightly insulated like a thin fleece. I have not tested it in rain but the hood has come in handy in light rain/snow out here. We tend to get big temperature swings here. It was 30 degrees this morning; 50 this afternoon; supposed to be 20 degrees tonight but I have been perfectly happy with this layering system. And it looks great. My biggest unhappiness with cycling jackets (and I have about a dozen of them collecting dust now) has been aesthetics and fit. The Swrve hoodie is well-fitted (it tapers nicely) and looks good enough off the bike that I wear it even when I am not riding.