SLADE

According to Slade's homepage:

Features Uses SDL/OpenGL for fast drawing and cross-platform compatibility

Some general 'Eye-candy' features Open Source Colour configurations Skins ;) 3d Editing mode

Planned Features

Improved editing features Support ZDoom's DECORATE lump

According to Doomworld : "Slade is an experimental Doom editor using SDL and OGL for its rendering. This is still a beta version. "

Note: Like Doom Builder, Slade has a 3D mode.

Click for slade screen shots