What does Islam say about life after death?

What does Islam say about life after death? There is this article on Wikipedia, but none of it is cited. There is a decent hadith that addresses parts of it on IslamQA , but can't really find anything else. I remember my teachers consistently saying something about everyone being tortured in the grave. Some say that good people who do certain deeds like praying voluntary salat get palaces in their graves. Some say that it is painless, like a dream, and that people will wake up not realizing that they have died (I believe some Quran verses suggest this theory). But there was never any good citation for any of this. So, my question is, what does Islam say about the experience in the grave? Not the part about paradise/hell, but specifically about what happens between death and the day of judgement.