Transmitting GPS data to Raspberry Pi
xbee is super simple, it is like a wireless serial port, just buy two of them, configure them to the baud rate of your gps receiver (sparkfun has MANY gps receivers (the GP-635T is very small, look at the picture of it on top of a quarter) on the host side get an ftdi breakout or something like that to get it converted to usb for the computer.  The xbee modules simply find each other and whatever is on the rx of one goes out on the tx of the other.  I have used the longer range models and gone well over 500 feet (require an antenna and of course the antenna choice has a lot to do with it).  Look at specs for the less expensive modules with on board antennas.