I've worked on some editors for Mega Lo Mania and Bloodwych in the past... both are useable but i wouldnt say they were release worthy yet! (maybe one day?)
I also looked into New Zealand Story level editing, but could only find a way to change the tile layout (no changes to entrance / exit / monsters etc)
Cannon Fodder has a good editor on Aminet, and the New Campaign level set.
SWOS has various editors used to update player data.