MCEdit 2.0 ID Fix is my altered version of MCEdit, the World Editor for Minecraft. I have tried to e.g extend the IDs of blocks which are usable from max 4096 all the way to 16384 which will make it work much better with modded blocks. About MCEdit: it allows you to edit every aspect of a Minecraft world, and to import and export .schematic files created by many programs including WorldEdit and the original MCEdit 1.x. It is free to use and licensed under the BSD license.
MCEdit 2.0's development is in the alpha stage. Many features may be buggy or missing. To download MCEdit 2.0 anyway, head over to http://www.mcedit.net/