This is a bit off-topic for this forum, but since many people deal with Arduino here, and checking the 'news' category might not occur, I'll post here as well.
I'm giving a workshop on extending Arduino's digital and analog pins, using shift registers and multiplexers, and collecting the data in Pd. The workshop is of course called 'Arduino-Extended' and will be held in Frown Tails, in Athens. More info here