If you are not a fan of Harry Potter, it's best to just click on the link to Martin Howard's collection web site (look to the sidebar). Otherwise, you might find out more about HP than you care to know...
From all that I have read and seen HP wizards tend to use quills. I heartily support the use of quills, but would there ever be a situation where a HP wizard would need to use a typewriter. Official MoM documents probably are written with a typewriting machine. O.W.L.s and N.E.W.T.S. were probably drafted with a typewriter before being sent to some sort of magical Linotype or offset printer. I believe there would be some situation where a typewriter would be used.
What type of typer would a wizard use? It would be easy enough to use a magical spell to make the machine work without direct manipulation from the user. In a situation where form need not follow any reasonable guidelines of usability, more eccentric and visually interesting typewriters would be the norm. The only visually interesting typewriter in my collection is a Blick 7. It has a magical pull on me, but there are some machines out there that would look perfect next to Dumbledore's Pensive.
The first would be the Norths. The Norths (as in Baron North) was British-made meaning it would be easy to have brought into the MoM without much problem. This typewriter looks like it would fit into a governmental office quite well.
Perfect for Ministry of Magic Offices, Hogwarts, Gringotts, etc.
The Columbia Bar-Lock would be a popular choice with those wizards who have a little more style. The Malfoys would need a Bar-Lock. The copper shield is very decorative and a little ominous. This typer is a visible writer, but you need to sit up very strait to see what you typed.
Great machine for Dark Wizards. Voldemort has two.
But the regular wizard who just needs to do a little typing might find this old Ford perfect. The touch is poor, but since a charm is going to be doing all the work it wouldn't matter. The grille on the front is friendly and fits into any home decor.
Great for authors, homeowners, enthusiastic amateurs. Molly Weasley uses one. Bathilda Bagshot used a Ford to write her book A History of Magic
All of these images are from the Martin Howard collection. Take a look at his very comprehensive collection. Impressive.