Wayne Grudem's Systematic Theology

Ok, I'll 'fess up and say I haven't read it all. Only the introduction and the chapter on angels (trying to deal with spiritual warfare at the moment!). But it's really good. It's not like mega-complex or anything, and is goes through Biblical texts pretty thoroughly (systematically, in fact!) It's only about £21 on Amazon too, which is a pretty good deal. Am going to tackle the bit on 'Satan and Demons' tonight (for the same reason as 'Angels') and will take it from there.
The intro was really clear and set out the case for what the book's trying to do. The stuff on Angels didn't have that much I didn't know in it I guess, but it was useful to have it all brought together and particularly to have the Bible passages behind what we believe :)

You might see it says 'over 250,000 copies in print' at the top. Well, mine says, 'over 300,000 copies in print' so I'm obviously not the only one who's bought it recently.