If you are still waiting for your Flex Builder 3 posters to arrive, you could do worse than print out a copy of the 'pocket' Flex/AIR reference Adobe just released.
At 20 double sided A4 pages it's a bit bigger than my pockets, but still makes a handy go-to book to keep on my desk - even printed on the plain old office printers the print is readable.
Page 4 has a handy 'show to people who ask what I do' diagram too :-)