Great response, Patrick!
I try to follow the frocks on bikes philosophy and look like a "normal" human being on my bike - I'm a commuter, not an athlete. I cycle most places I go, including to and from work everyday (about 20 minutes each way) in central Auckland and generally don't change what I wear because I'm going by bike. My denim mini skirt is ruled out, of course, and I avoid wearing jandals for safety reasons, but just about anything else goes. I find I'm actually more comfortable riding in heels than walking in them, and I'm grateful tight jeans are in fashion, because they're good for cycling in - better than the flares I used to wear a few years back, which risk getting caught in the chain!
A good, waterproof windbreaker is an absolute must for cyclists in Auckland - nowadays I hardly leave the house without one. I also keep a spare pair of jeans by my desk at work in case I get completely drenched on my way in.
I much preferred cycling in Europe without a helmet - even when sharing the road with crazy Parisian drivers - but I wear one here, mostly because of peer pressure (there's plenty of conflicting research about whether helmets increase safety, and I would rather have the wind in my hair, but most NZers seem to think you're insane if you don't wear one). I never wear lycra, high viz stuff or anything with reflective stripes - I reckon it's much more important to have a good front and back light for riding in the dark.