For that kind of thing I would just angle the cross-slide. And then there is off centre turning. A tape attachment is a great thing for certain uses though.
A cool thing is to make a thing that holds a dial indicator in your lathe toolpost at centre height, then you can drive your toolpost back and forth on some taper you want to replicate, and then when you are dead zero on your model piece you will be dead zero on your cut. It is also a great way of measuring whether your tail stock is dead nuts with your headstock bearing, which is important if you want cut parallels or tapers accurately.