Also, dynamic memory is generally just teeny tiny capacitors. You charge them to write (if you want a "1" in there), and then read the voltage back. But they're small enough that they lose the charge pretty quick, and have to be constantly 'refreshed' by reading and re-writing.
It's not 'hard' per se to interface with them, just more of a pain than most people want to go through. (Especially since it only takes one late refresh to completely corrupt whatever you have in memory) There are chips especially designed to do nothing but babysit the DRAM so the processor doesn't have to... But I have no experience with using them directly. Maybe there are some suitable for the AVR.
I think I am, therefore I am... I think.