Instead of writing my final degree project, I've spent the afternoon reading about lisp, and I found out that to learn lisp (in fact, to learn any language), it better to get a book and read it throughtfully than read a bit from here and a bit from there.
Maybe it's because I've already read a bit from here and a bit from there, now I can read 3 or 4 chapters in a row from a book.
Anyway, I'm going to put here a couple of them that seem specially good:
Ansi Common Lisp : Not free, but you can get the first two chapters for free from paul's site. Reading the first 100 lines conviced me about it. great style of writing and going right to the point.
Successful lisp: Free. Great (at least the first 3 chapters) Very well explained, and with good and well thought examples and code listings