XASTIR

Xastir is program for receiving and plotting APRS position packets. Development is a collaborative effort of programmers and amateur radio enthusiasts from around the world. Xastir supports many map formats and is highly customizable.
Xastir runs on Windows/MacOSX/Linux/FreeBSD/Solaris/Lindows. It supports 125 map formats, several types of TNC's and weather stations, Festival speech synthesizer, AX.25 networking (Soundmodem/Baycom/SCC!) and seven languages!.