As Bloodline says, AMOS is not really something that I'd want to start learning now. Sure, you can get a fancy rainbow effect with a few lines, but even AGA screenmodes aren't supported (AFAIK there are extensions for AGA support, though I've never used them) and you can give up any ideas of writing programs that'll work well with non-custom hardware, AmigaONEs, Pegasoses (sp?), AROS or Amithlon
BTW I started a short tutorial on the wiki here - if anyone feels that they know more about BASIC than I do (likely) then feel free to edit it.
Hehe, I know that much basic. I dont want to boost but im pretty good at basic. Thats the only programming language I have mastered though...
Btw, wont Amos games run on emus on the newer systems? JIT emulation should be fast enough.