My choice was a Chrome Citizen messenger bag, all in black. The size (20 liters) feeds my daily needs perfectly. In case of big shopping trips I still have my additional carrier. Why in black and not in a more flashy color? Well, black is elegant and fits all my clothes (they are quite colorful anyhow :-)). Plus, if my bag gets dirty (which happens in the winter a lot) that's hard to see on black. In bad weather conditions other colors may be more useful, but the bag has some reflector bands anyhow.
What I particularly like about my Chrome bag -- apart from weather resistance -- is that it has many different compartments. The cool and comfy shoulder strap (available for right and left hander, by the way) makes it easy to open and close the bag without having to take it completely off. And I can attach my digital camera to the strap, so it's always within reach :-).
What I don't like is that it has no small compartment outside of the big flap. Sometimes it would be nice to have a pocket where I could reach my keys easily (especially when I cycle in skirts that have none). Although the bag is big enough for me, I guess I would go for the slightly bigger model now -- the Chrome Metropolis. Those who don't like the "over the shoulder" design may want to check out their messenger packs instead.
More Information: Chrome International and Chrome Europe
I ordered my bag through Busy Bag (Germany) and received it within 1 (!) day. In Austria there is only one bike shop that I know of that sells some Chrome bags: Ciclopia in Vienna.