Notices

Opera mini DOES reduce traffic as well. It strips down the webpage and compresses as well. Sometimes the processed data is less then 1/5th of the original page.

You can use transcoding HTTP proxies like Rabbit or Ziproxy as the tablets support ordinary proxies.
I am using ziproxy to reduce data over the slow GPRS link to speed things up a bit. It is possible to gzip-compress text content and recompress/reduce quality for images.