Table of Contents
Clients
For testing purposes you should use the OSI Client at the moment.
OSI Client
You can run the original (OSI) client under GNU/Linux with the help of Wine (see http://appdb.winehq.org/appview.php?iAppId=228).
There was a download called uoml_setup.exe called Mondain's Legacy which contains Client Version 4.0.11c (Patch 0).
You can download a client from http://largedownloads.ea.com/pub/uo/uoml_setup.exe
http://largedownloads.ea.com/pub/uo/setup-1.46.0.3.exe.
After installation you have a client v6.0.1.10 (Patch 72).
There also seems to exist an god client: http://necrotoolz.sourceforge.net/kairpacketguide/godcli.htm
Wolfpack Client
The current version (build 72) is based on QT4.
apt-get install libqt4-dev qt4-qmake libopenal-dev libalut-dev
Perhaps there are some minor changes in uoclient.pro nessesary.
qmake make
After compilation the file uoclient exists in the current directory.
Move it to the release directory and start:
mv uoclient release cd release ./uoclient
You get an error, but the configuration file config.xml is created. Update that file to fit your needs: edit your server IP and the path to the UO installation. After that you can copy the file to your home directory and afterwards start the client
mkdir ~/.UO mv config.xml ~/.UO/config.xml ./uoclient -c ~/.UO/config.xml
To be standards compilant one should move uoclient to /usr/local/bin, the UO-files should stay in /usr/local/share/UO, the wolfpack stuff perhaps in /usr/local/share/wolfpack and so on 
Iris2 2D/3D Client
see: http://www.iris2.de/