Thanks Bobby for your kind words. Unfortunately I've been flat out with some contract work and if I frequent the forums, I find myself staying up all night excitedly doing some new tool or investigating something.
That reminds me, I also have two more tools I did that I haven't put in this thread yet, inspired by a functionality Mike needed in Unity at some stage:
1. Splat map resolution changer: A tool that allows you to change the resolution of the splat maps without losing all the terrain painting you've already done. Splat maps are simply maps that Unity uses to internally know where textures have been painted on the terrain and at what opacity. The 'control texture' resolution you see in Unity's Terrain settings represents the resolution of these splat maps - the higher it is, the smaller the 'splat' of paint can be that gets laid on the terrain when you click the mouse.
2. Heightmap resolution changer: A tool that allows you to change the resolution of your height map without losing all the terrain sculpting you've already done. I believe it's nicer to start terrain sculpting with a very low heightmap resolution (eg 257) to get the lay of the land and rough mountains quickly sorted out, then change to a high resolution to do finer sculpting. I used to export the raw map to Photoshop, resize it and reimport, but this tool just allows you to type the new resolution in and it resizes it.
Both tools use bicublic interpolation instead of linear, a fancy way of saying smooth painting and sculpting is maintained.
Until I get a chance to document them properly on here and upload, just PM me if you have a sudden need for them.