Arduino and rs232

Hi, is there any way to transfer data to Arduino (and back) using RS232? I have Arduino with USB and I'd like to use it even on standalone ATMega. Thanks. (sorry for my english)

Sure, add an RS232 module:

Connect D0, D1, +5, Gnd.

If you're using for Serial uploads, will need to press Reset on the Arduino when the IDE displays "compiled xxx of 32xxx bytes" or similar message.