The most widely-used form of Packet Radio, APRS lets stations transmit periodic position beacons, send messages, and other information and forms a self-organizing Mesh Network with the possibility of propagation by both radios and, less frequently, Internet.
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The TH-D72A is a very nice handheld Amateur Radio Transceiver. Among other things, it has an integrated GPS, built-in APRS functionality, full AX.25 Packet Radio TNC, and a USB port (which shows up as a serial device) to a computer – all built in.
WinLink 2000 is generally designed for HF communication, but they have a nice APRS gateway as well, enabling short messages to be sent to and from email accounts from APRS users.