Latif Khalifas mono viewer for Second Life and opensim grids
Lightweight client for connecting to Second Life and OpenSim based virtual worlds.
Radegast is feature rich GUI client. With it's full support for all communication within a virtual world (chat, IM, group IM, friends conference) it's ideal for situations where full 3D client is less than ideal solution, for example, an office environment, too slow a machine and similar.
It's written using libopenmetaverse, and it runs on any platform that supports .NET/mono. Its being actively tested on Windows and Linux.