JTelnet is a simple telnet library for Java with a few demo applications. One is a simple command line telnet, another is a Swing component that includes VT100 emulation.
FreeHost3270 is a complete 3270-to-web solution, providing single-point deployment of legacy 3270 applications to unlimited clients. It delivers either a java applet-based TN3270 emulator, or a stand alone application with rich GUI.
The goal of Slipper is to control peer to peer applications on a remote server. This might be of some use to people behind firewalls and proxies and are being banned on some ports (ie napter, gnutella), but ftp and telnet ports are still available.