Generic parts?

[kresty]

Are there standard parts that are used in lots of different things? eg: if I wanted to look at stepper motors, are there some that are in many things (eg: 3D printers/CnC/robots), or are they all different things?

I saw an instructables savage mentioned http://www.instructables.com/id/Build-a-30-laser/ and see that the parts list includes a cheap Chinese stepper.  I haven't really played with those, but if they're "standard" maybe that's a model I should look into?