W4MQ and W7DXX have connected their HF radios to the Internet. With the software on their sites, you can have full, two-way control of their rigs and make contacts through the Internet.
EchoLink is a fabulous system that uses the Internet to remotely connect repeaters. Users can connect to the remote repeater using their computer and the EchoLink software, or by using a radio to connect to a local EchoLink node and using DTMF tones to connect to the remote node from there.
eQSO is like EchoLink, but has much fewer users. IRLP is also like EchoLink, but only allows users to link to a remote repeater using a radio.
-David / N9KT