pcmanfx

An extension specifically designed for Telnet/BBS browsing. It let you use telnet:// inside Firefox tabs.

Features

• Entirely written in Javascript. No additional plugin is needed.
• Cross-platform, can be used on all platforms which Firefox supports.
• Seamless integration with Firefox
• Reasonable execution speed
• Good render quality
• Can render one double-byte characters with two different colors
• Actively developed