It's time we had fresh discussion, and what better than a series of links?
Atomic Rockets - This is a website for aspiring science fiction writers, but it goes into a level of detail that I have never seen elsewhere. A valuable resource for anyone remotely interested in space exploration.
Bad Astronomy - Professional astronomer Phil Plait takes a look at common misconceptions related to astronomy, including some found in movies, on the news and on TV.
NuclearSpace - resources and articles relating to the advocacy of nuclear-powered space exploration. Currently being redesigned.
Centauri Dreams - the News Forum of the Tau Zero foundation, an organisation which advocates human exploration of outer space.
Orbital Vector - A catalogue of various technologies, ranging from near-future possibilities through to more speculative tech.
Feel free to add your own links!
As an interesting news site we could add NASA I don't have many other astronomy links.
Stardestroyer.net - Another fiction-oriented site, but includes some interesting essays and useful calculators.
Additional additional: Beyond Apollo is an awesome blog which I recently discovered, which discusses plans for space exploration from the Apollo era onwards. A real find.