I am doing the same kind of trip starting 1st august with 3 mates. We are starting in London, getting the eurostar to brussels, then trains and buses through germany, czech republic, poland, lithuania, latvia, estonia and to st petersburg. From there getting the trans mongolian express through mongolia and to china.
The plan is then to travel down through china, vietnam, cambodia, laos, thailand, malaysia and singapore by train. I believe we can get boats around the indonesian islands as far as east timor, but as yet i havent heard of any boats/ferries going from east timor to darwin! If anyone knows such things exist, please inform me.
I only planned to get as far as oz without flying. Hopefully travel around there for a year or so, and then see how much further my savings will get me i suppose. would like to see south americas as well, but that might have to wait until ano0ther time.
Feel free to keep in contact as you may be able to learn from my mistakes if you are doing a similar route!