Really interesting report on Oxfam shops and how they deal with donated clothing. Apparently bras are really in demand because in developing countries there's a shortage (mainly because they are complicated to manufacture). So there's a ready market for secondhand ones. I had always thrown away my bras, thinking nobody would want to buy a s/h one, not to mention that the likes of ebay won't accept secondhand underwear, but have just sorted out four that can be taken down now.
The clothes are sorted first for resale in UK shops, or ebay if valuable/vintage; then the remainder are either baled up and sold to small dealers in developing countries, or at the last they are sold for fibre recycling which Oxfam also get paid for.
I thought this was excellent, previously I had looked at cast offs and thought, perhaps it wouldn't be saleable in a charity shop so had binned them, but now I will pass on everything as it's unlikely to be wasted.