Most of my caches hidden between 2001 and 2008 use a white translucent waterproof Nalgene container, 500-900 mL (about 1.5-2.0 pints) in volume. I find these containers quite robust to water and damage, but the tradeoff is in their size. Many geocaches are larger than this size, but seeing that I hide a number of my caches internationally, I often need to carry these caches to their final destination via air. As such, the caches cannot accommodate large cache objects, so if you plan to bring something to trade, please make sure that it is no bigger than about half a fist in size.
Learn more about my caches on my Geocaching page.