I found a portable intercom that I carry around in the plane with an
audio out and a digital voice recorder is a fantastic investment.
Recording your own flights and reviewing them post flight is a good
tool. It also can help the flight instructor as well. You can hear the
calls you missed or where unclear about in a low work load environment
after the fact and honestly evaluate your performance. A portable T/RX
(or scanner) in conjunction with the comm and recorder also works
well. You can get hours of radio trainning tapes (CD's) for pennys.

Jon Wanzer
CP ASEL / IA
AGI IGI (CFI / CFII soon-to-be)
San Jose,CA