In addition to EchoLink there is IRLP (ARRL repeater directory will list IRLP nodes) which also uses V/IP and works rather well. The only problem I have heard (I've never worked IRLP or Echolink) is that some nodes are "Hotter" than others audio wise, so sometimes I hear the distant station soft and the local threatens to blow my speaker, sometimes it's the other way around. This is operator adjustable however.
Echolink works much the same as IRLP. I have listened to Echolink as well Same comments
There is also straight Ham Radio from your computer... This normally requires you set up an account (Free) with the host radio node. You will need to provide the host with your name, address, call and contact info, along with a sign on (usually your call) and password. No call, you just listen
I'm finding it more fun to run Ham Radio from the 2nd restroom on the Motor home though

Yup, I put my righ where you go when you got to go so when you got to go it don'e interuppt the qso