The best outerwear I have found for doing any type of sport in inclement weather is snowboard clothing.
The 'shells' tend to be relatively lightweight, breathable and often very 'technical' (read: lots of pockets and zippers, including underarm zippers for ventilation).
They won't stop a real honest-to-goodness downpour, but then again, nothing else will either, unless you're willing to sweat like a pig on a spit in one of those yellow sou'wester type things, getting you wet either way......
Snowboard stuff also tends to look a little more 'normal' than a lot of the clothing specifically made for cycling, which means you'll be more suited to walk amongst your fellow humanoids (if you must...).
Wool is great as a first or only layer or when it's REALLY cold, otherwise too hot, and the really thin wool shirts and undies cost an arm and a leg.