And apart from Adobe Flash ....
While the discussion thus far seems to have been focused on Adobe Flash - I can thoroughly recommend Cute PDF Professional as a replacement for Adobe Reader. It has a neat "typewriter" feature which allows you to annotate existing PDF documents which I find very useful. It's not free, but well worth the modest amount to get out from under the dreaded Adobe with its outrageously huge update sizes.
Works for me - your mileage might vary.