I've noticed that using bzip, cranked up to it's max level, is really effective for compressing dynamic HTML. I've managed to achieve what I suspect is comparable to Railgun by simply having this compression applied on a multiplexed TCP tunnel in rather large blocks, so that packets from multiple sessions are compressed together. It worked really well, it enabled me to offer reasonable fast content delivery to clients with servers on small leased lines in Africa. I found it a hard service to sell, it takes a lot of explaining ;-)