I have found a good bra camisole to be an excellent item to have when doing summer outdoor activities, particularly hiking.  When we lived in Alaska it was quite common for us to set out on a day hike up into the mountains where you had to be prepared for all kind of conditions – it could get really warm but when you got high enough there would also be patches of snow.  Having a good bra camisole with good support and coverage such as the ones sold at REI meant that when it got warm you could strip down to that level and still look sporting and modest – it saved having to have that one extra level of clothing.