Here making buttermilk. (Though Balloon whisk is what I normally use for that.)
This one is from Braun. If I had to choose just one appliance (over and above the mixie!) this would be it.
Comes with a balloon whisk attachment, and a chopper. Has different speed settings, especially useful with the whisk.
The blender is almost entirely in stainless steel, making it very convenient to consider churning up soups right in the cooking pot.
Also an invaluable tool for making quick purees, shakes and other liquid blends.
Much easier to clean than a mixie jar.