I've travelled in a number of countries where women in western dress could be harrassed.  In India I actually wore clothes I knew I would throw away (actually, I left them on the outskirts of a slum in Delhi, so hopefully some use was made of them, if only as cleaning rags) I packed lightly and bought some Indian clothes as soon as I arrived-the pants with the overdress are really comfortable and cool and the bonus was that I was approached by Indian women who wanted to know what I thought of outfits and generally interact with a woman from a different culture.  The men seemed to respect the traditional dress as well, a number of girls who wore shorts and skimpy clothes found themselves in tricky situations but I found I could interact with people without ever feeling threatened.

In Turkey I met some girls who complained about constant harrassment, but they didn't seem to realise that a well endowed girl, without a bra in a singlet type top could be the reason for that harrassment-I was just as well endowed, but wore a sports bra and baggy clothes that didn't show off my curves and I didn't have any instances of unwanted attention (though I still managed to get some wanted attention when it suited me). 

I've also travelled through many African countries without incident, however in Egypt I had some instances where I was bartering and having some good chats with shopkeepers but I always made sure if they overstepped the line and tried to touch me inappropriately (even if only on the knee) that I immeadiately stopped any negotiations and left the shop without making a purchase-at times this was very difficult as if you are indignant enough they think they can buy your silence with a really cheap price on whatever was the article we were bargaining over.  But I always felt it was important for them to realise that it was not OK for them to touch a woman inappropriately and I hope my reaction may have made them think twice about attempting the same thing again.

I think the main thing is to respect the culture of the country you are visiting-if it's a Muslim or conservative country then don't think you can go topless on the beach or show off your shoulders or your belly button or your legs or your tits without some repercussions.

I cannot agree enough with what you said!  I think we sometimes value our freedom of expression so much that we forget that part of being free is respecting other's choices and views.

I had similar experiences in Egypt.  The other girls on the trip were not dressed immodestly, but they were not hiding their figures either.  They often reported problems while out shopping, but I only had one incident.  I did the same thing you did--left the shop without buying anything and when the man followed me out and tried to grab my arm I told him to stop or I'd call the tourist police.  He quickly backed off.

 When I go to Africa I like to go to the Salvos or Angli Care shops and buy cheap loose skirts that reach my ankles, or close to them.  Then I leave them with missionaries or peace corp volunteers to be given to those who need them.  It helps to remember that while things are changing, in many African countries only the prostitutes wear pants or short skirts.  By walking around in pants, shorts, or short skirts you're actually advertising yourself as for sale!

Respect is the big thing.  If the local dress is comfortable (and that of India is!) and affordable it's also fun to wear it.  But at the same time, it's not necessary to wear a burka.  Finding the middle ground can be tricky, but is well worth it!  Having a shawl or long scarf handy while in muslim countries is also good so you can quickly cover your head if you find yourself in or near a place of worship or religious ceremony (and it's also good for keeping warm on those cold nights).