Where to find basic but useful information on space and space travel

This site here is quite impressive, answering many basic questions on space and space travel in easy-to-understand language, and covering quite a few subjects. It's actually from the Astronomical Institute at Utrecht University, and the same information can be found in Dutch as well. Definitely bookmark this site if you feel like taking the time to go over some basics on space but aren't sure where to begin.

One part in particular I like is the bit about payload requirements for getting to the Moon and back, because though the Moon is still quite the gravitational well compared to many other destinations in the Solar System, it's still fairly easy to return from considering not only the lower gravity but also much smaller payload on the way back, since on the way there one needs to take the ship for the return home as well but on the way back it's a one-way trip. For the Apollo program this meant 3 million kg and 110 m at launch, but only 4900 kg and the height of a house for the part that took the astronauts home. Or, to put it another way, the launch from Earth required 52 kg of fuel for each kg of payload, while this number on the way back was a mere 0.9 kg of fuel per kg of payload.