i don't know if this has been posted before, but i figure this could be something to help anyone curious about the X-Men's extensive history. maybe one of the mods would want to put a sticky on this for easy access.
this is a list of Marvel's complete (sort of) X-Men chronological reading order for any book ever featuring a mutant. it runs all the way to the end of Messiah Complex so its still fairly recent. it also feature Marvel's readjusted timeline (according to this the X-Men were founded around 1990). i thought that was really interesting.