Monster Converter is a Chisel plugin that lets you avoid an unpleasant quirk in Forge. When M1 maps are converted to M2 or Infinity maps, Forge ignores the fact that the monster order changed... so you have to go through your maps and click every single one to convert it. (Or you have to nuke the map.) Monster Converter fixes this. This plugin is also available as part of the Chisel 2.1.6-enhanced package.

Poseidon is a Chisel plugin that lets you flip a marathon map (M2 or Infinity) around the X, Y, or Z axes. Pretty slick, actually. Version 1.1 fixes a number of small bugs. This plugin is also available as part of the Chisel 2.1.6-enhanced package.