Oli,
I believe that some of the features you want can be found here
http://github.com/radiant/radiant-page-attachments-extension/tree/master
or http://github.com/kbingman/paperclipped/tree/master
One could start with either of those and add your missing features,
but I don't know of any
Oli,
paperclipped definitely does about 80% of this. Importantly it makes
very good looking thumbnails and you can customize the crop and size.
It also does not require rmagick, so it is a bit lighter weight on
RAM. I have been recently doing some drag and drop work as well, when
you
