It is highly recommended that new players make use of a MUD client, as Telnet clients (even those which may be more fully developed), are not designed with the tips, tricks or mudding specific features in mind that are sought for in MUD clients, see MUD client tips.
The Java client on the Discworld MUD website is a simple and free browser-based client. It connects only to Discworld MUD. It supports colour, scrollback and a command history and is a good starting point for newcomers. However, it lacks many of the useful features of other clients, such as triggers, macros and copy-and-paste.
Lyntin is an open source Python implementation of TinTin, with an eye for extendability. It supports all the standard features (though you need to download an MCCP plugin, it doesn't come by default) and is easy to modify with even a little Python knowledge.
Mudlet is a free, open source MUD client. It has been designed and built from the ground up to feature ease of use, a powerful scripting engine, and a lightning-fast display. It supports MCCP, MXP, and a host of other MUD-related protocols.
CMUD is a commercial MUD client for Windows XP SP2 and Windows Vista. It costs US$29.95 and has a 30 day free trial. Its features include aliases, macros, triggers, scripting, automatic mapping, capture windows, logging, MXP, MCCP and gauges.
MUSHclient is a free and open source client for Windows 95/98/ME/NT/2000/XP/Vista. Its features include include aliases, macros, triggers, scripting, logging, MXP and MCCP.
Pendrake's Discworld MUD Pages contain many useful plugins for MUSHclient.
Garrion's Plugin page has some too that use the new miniwindow feature of MUSHclient 4.40. These are based originally on the plugins found at Pendrake's site.
VIP Mud ($30) is a powerful MUD client, specifically designed with the visually impaired user in mind, although anyone can use it. It includes builtin support for speech output to a variety of screen readers, whereas other clients would require plugins, addons or screen reader modifications to get the same functionality. Other functions are a very simple, yet powerful scripting language, aliases, the ability to gag certain lines or substitute them with something completely different, key mappings/macros, speedwalk recording/playback, support for sound triggers, session logging and more.
zMUD is the precursor to CMUD, it is no longer being developed but it shares most of CMUD's features and is considered more stable. It is supported on Windows 95, 98, ME, 2000, XP, and NT, but CMUD is recommended for use in Windows Vista. It costs US$34.95 and has a 30 day free trial. An earlier version, lacking many of the features, is available for free.
Linux and Unix
GnomeMud is the GNOME client. Its features include macros, triggers, scripting and MCCP.
KildClient is a free GTK+ client. Its features include GTK-Spell based spell check, Perl-based Plug-ins, extended aliases, macros, triggers, scripting and MCCP.
KMuddy is the KDE client. Its features include macros, triggers, multi-language scripting, partial MXP support, MSP sound and MCCP. It supports IPv6. KMuddy will run under Gnome as well as KDE, but viewing the documentation under Gnome can be a problem. See an on-line version here.
TinTin++ is a free command-line MUD client. Its features include macros, triggers, scripting and MCCP. TinTin++ supports IPv6.
TinyFugue is a free command-line MUD client, but it can be very difficult to master. Its features include macros, triggers scripting, and MCCP. TinyFugue supports IPv6.
Vashti's Web contains several useful macro packages for TinyFugue, some of which may require minor modification to work with recent-ish changes to the MUD.
Mac OS X
In addition to the clients below, it is often possible to compile Unix clients under Mac OS X.
Atlantis is a Cocoa-based client for Mac OS X. It is currently free and in open beta, but is expected to be shareware on release. Its features include multiple 'spawns' (capture windows), shared world settings, Growl support, logging, triggers, macros, aliases, Perl scripting and MCCP.