This is not a full WON replacement, but it does the most important thing: It lists servers!
To use in your half-life, you have to download this
woncomm.lst and copy in ito your "Valve" folder in your Half-Life, replacing the old one.
Now you can just click on
Multiplayer -> Internet Games, and there on the button
Update on the left side. There should now be a list of all known Counter-Strike Beta servers!
Servers listed on the Master are the same as on this
Server List.