I've wanted a Dexter forever!
They, and another breed I can't name off the top of my head right now, that they are "from", aren't "bred" to be small, like human tinkering, but are a breed that originated in Great Britain somewhere, and are a small and hardy breed - like Shetland ponies from the Shetland Isles. They are small, strong, and multipurpose - had to be to survive the pretty nasty conditions they lived in - bad weather, poor food availability, crazy terrain.
They are considered a breed that is good fro dairy, meat and draught - work. They have good muscling for meat use, high butterfat for milk use (not has high as Jerseys I think) and are generally a good temperament, so can be trained to pull things, like one would think of oxen.
Looked it up and the other breed is Kerry.
If I could talk DH into letting me have a cow, there is no doubt that's what I'd get. I even know what breeder I would contact for one
About Dexters:
Dexter Cattle - South East Group // Info
More info here (US site)
Triple Purpose Dexters