Hey Peter,
build a wireless data recorder to open some cars...
(take the 434,92 MHZ or 868 MHz Modules from Radiometrix TX2 and RX2)
The speed is good to calculate the bits and for some better systems the hoping code. The Bandwith is up to 40 KHZ on some systems.
I have developed last week a biphase mark transmission and i have received enough code of my neibourhood (from cars alarmsystems....all without hoping code....wondering !!!)

You can do a good crypto decoder with the chip, because you need speed and RAM for calculations.(and the arithmetic is good on 8052 to do that)

good look,
Sascha