I was wanting to make some novelty items (chess pawns & an ornament stand) on my lathe and needed to turn a taper up to a flat face, I studied the work done by Brian and Kiran and came up with these. Use with extreme caution, I haven't tested these very well. Practice on wood, plastic or air first!
They are also useful if you just want to do a taper and don't know the angle, just the start and stop on x & z.