dtelnet - Open source telnet client for Windows 16/32.
EasyTerm - A freeware Telnet terminal client for 32-bit Windows.
Ericom - the developer of the PowerTerm series of terminal emulation products. They support a full line of emulation types, including IBM (TN3270E, 3270, 3278), Digital (VT520, VT420,VT320,T220), Wyse and General Data.
J-Term Professional - Shareware telnet client for Windows with Pascal-based script language and an FTP client.
MochaSoft - Software development company specializing in communication software. They sell Telnet, TN3270, TN5250 and LPD products for Windows-95/98/3.11, Macintosh, Java and PalmPilot.
Nexus Mainframe Terminal - A telnet 3270, 5250, VT and ANSI terminal and printer client. It also includes a FTP client. It has support for recording, script and HLLAPI, and the LPD protocol is supported by the printer emulator. Both the terminal and the printer emulator have support for SSL.
PowerTerm InterConnect - tn3270 and tn5250 terminal emulation software for IBM terminals.
Pueblo/UE - Free, open source client for Windows with support for in-line HTML.
PuTTY - A free telnet and SSH Client for Windows and Unix platforms. Includes FAQ, documentation and contact information.
Rudenko ShellTelnet - Windows-32 Telnet client for use with a Unix shell account. It shows Unix files in a Windows Explorer manner for easy navigation and file management.
Tera Term - Free Telnet client for Windows (16 and 32 bit). Source code and a Secure Shell extension available.