-IO ports (including pin interupts), 8 bits timers (well, one of mode of the myriad),
-SPI master & slave, and the UART with tx&rx interrupts.
+watchdog, self-programming (ie bootloader), external interrupts (INT0 etc),
+IO ports (including pin interupts), 8&16 bits timers (well, some of the modes),
+SPI master & slave, ADC, and the UART with tx&rx interrupts.
+
+The only notable missing bits are i2c and XMEM bus access (for the big Megas)