These are mostly MUDs on which I know Wintin is used, either because I have played there myself or because I've had mail from people who do.
If your favourite MUD isn't listed here, let me know. If you give me a three or four line description of it, I'll include that as well. The links in this section are to home pages: where I don't know of a home page for the MUD I've put its telnet address in brackets.
Sloth III is a multiclass DIKU MUD with a total of 160 mortal levels. The areas are original and written to a high standard. I play, code and build on Sloth III - so you won't be surprised to learn that it's my favourite MUD and Wintin works very well on it :)
Valhalla is interesting because it's based on Diku II - the official extension of the original Diku code. The web site is well maintained and has some information on the current activities of the original Diku coders.
In the words of one player, 'Alter Aeon is a great mud with ansi color and is always being updated. The code was written by Dentin (god name). Check it out. :)'
One of the oldest running MUDs around, up since April of '92. It has 50 mortal levels and 10 immortal levels, 4 classes (W,M,T,C) and lots and lots of rooms, mobs, spells. Grimne has also been enhanced especially for grouping, even though a character of any class can still be good for soloing.
HEAVILY modified DIKU based MUD. Pkill & Pthief encouraged. Many unique and dangerous zones, spells and item affects.