This is a list of all the filters (plugins) I've written for MCEdit. You can download MCEdit here.
Create a cross section of your circular structure, then apply the filter. It will rotate the object around the center of your selection.
Select any entities and this filter will turn them into mobspawners that spawn those entities.
Change one or both effects on your beacons. You can also set the level.
Put items into a chest or dispenser, select it, and add custom enchantments.
Scale terrain up in size. This is mostly obsolete, since you can do the same thing with MCEdit's clone feature.
Generate python code that will recreate all selected entities and tile entities.
Select dispensers and it will fill up any occupied slots to 127 items. If there are empty slots, you can have the filter fill those with a default item as well.
Finds text on signs and command blocks, and replaces it with other text.
If the bottom of your floating island is flat, this will make it look like it was ripped out of the ground.