it would be nice if mods like this could be plugged into in some way.

Also, is there a way to tell starvation ahoy about other mod's crops so it can make them "dirty" upon collection?

http://minecraft.curseforge.com/projects/simple-harvest

I'll look into making a patch for it. There is no way for a user to add in dirty crops, however mods can integrate with a simple FML Intermod Communication