City or country I feel vulnerable without a mirror. (More
vulnerable, I should say.)
The best solution I've found for dropped bars is the "Ultralite German Mirror by D+D Oberlauda", which you can find from a number of sites on the web. (In North America I think it's sold via Ortleib.) It's light, gives a sharp image, and — the thing I like most about it — is very steady. (Helmet mirrors make me dizzy.
) I have one on the traffic side of both my bikes, with a little "Zefal spy" on the curb side when I'm likely to have to deal with multi-lane roads.
It's actually quite handy when I switch from riding in Canada to touring in Britain: I switch the mirrors over and it reminds me on which side of the road I'm supposed to be on and where to watch for traffic.