sup/tg/ offers a variety of ways to connect to other fa/tg/uys for online tabletops:
The sup/tg/ IRC can be found at irc.thisisnotatrueending.com on ports 6667 or 9999. You can use the embedded Java IRC client here to connect if you don't have an IRC client.
We have a Teamspeak server for voice chat, which can be found at thisisnotatrueending.com (password lolts, login type anonymous). Here's a screenshot of the configuration page for connecting:
sup/tg/ also offers PaintChat, a collaborative drawing tool written in Java. As the program hasn't seen work since 2003 and lacks a number of important features (like a built-in permission systems to prevent trolls or accidents from ruining others' artwork), please contact me via IRC for a login if you'd like to participate.