MindTerm - Complete SSH-client with a vt100 terminal. [Open Source, GPL] - http://www.appgate.com/products/80_MindTerm/
Java(tm) Telnet Applet - Provides VT320/ANSI emulation. It can be used to provide access to telnet services via a Java capable WWW browser. [Open Source, GPL/LGPL] - http://javassh.org/space/start
The Java SSH/Telnet Application/Applet - A Java implementation of telnet/SSH and ANSI/vt320 terminal emulation. [Open Source, GPL] - http://javassh.org/
JET Terminal Emulator Java Applets - IBM 3270 and Tandem 6530 terminal emulators and APIs for the Java Platform. (Platypus Partners) [commercial] - http://www.platypuspartners.com/products.html