I say the useful functions from -xplicits- (I think I may had spelled wrong) and other multi-tools is:
the cleaner (removes unnecessary files)
the CBL checker (clan and player, preferably one that does not need to open up in a browser to see)
Temporary no-textures mode (makes screen environment, player, etc white) with the temporary removal on the shader file (RS.rez I think it was called) [this allows you to see Viper when in no-texture mode]
And I'll say the ability to go into windowed mode...if there is a working one.