In the modern cooking age we are pretty inundated with tons of gadgets. From weird things like avocado slices to egg slicers, you probably can buy any gadget imaginable.
Oddly enough the attachment that has really stood the test of time is the magic bullet. In particular are two attachments that stick out.
On the left is a wide blade. With this you can purée things into a fine sauce. Good uses would be like a red pepper sauce, celeriac sauce, etc.
The one on the right is a grinder. With that you can make you own shabu shabu sesame sauce (Goma Tare), and grind any seeds or nuts into a fine texture.
Where the magic bullet beats a vitamix is where you are able to work with smaller quantities.
I also made my own Thai curry paste, but one side effect is the staining of the plastic with turmeric.