If we're talking guide books then you can't fail to have noticed the lonely planet. They come complete with a free pair goggles that give you a whole new view the world (restricted)! Even so they still provide by far and away the best, most relevant and comprehensive information you're likely to find at the scumbag end of the travel market. Just promise me you wont over use it. It's a hard habit to break!
There's also a very handy website which has a message board as well as handy regional hints from fellow travellers.
In Your Pocket is a top quality information site chock full of useful info about the Baltic region, Central and Eastern Europe.
Expedia is a good place to get an idea for flight prices. It generally lists a whole load of flights that are among the cheapest around, you can compare prices from different airports and mess around with your itinerary 'till it suits you.
Bridge the World are an independent travel company I sometimes use. They specialise on Trans-Siberia trips, which is way up on my list!
