Looking to learn assembler programming, any advice?

Hi everyone, I've been a hobby programmer for several years now with experience in various high-level languages (Java, Python, Lisp, a little C/C++). Recently I've been toying with the idea of learning some x86 assembler programming. I know it isn't really much used anymore, but I would like to learn it for the sake of getting to know my computer better.

Unfortunately, I have no clue where to start. Any advice on possible directions to pursue would be much appreciated. Books, tutorials, software to install (I'm running Linux), other hints... Thanks in advance :-)