It's called "an ash," and has fallen out of English usage. When I was a kid I used to see it in archæology and æsthetics, but no more. And even in this font, it's coming through too small, and not taking it's proper width.
With half-spaces in a typewriter, it worked well to type Ælflæd (my SCA name) or Træskæg (our friend Sigmund Træskæeg / Marty Tuft's SCA name). You ended up back on track and the end, for having used two half-spaces.
At the grocery store near us is a sign on the door, so I see it often.
I pronounce it in my mind "eee-yay-it" but they intended for it to say "exit." Someone at a sign company discovered that character and assumed it was a fancy "X".
There are names still around that were once spelled with that letter. I think "Ælflæd" went out of style for a girls' name 700 years ago or so. :-) But Elsie is still around (Ælsie). Schuyler Waynforth has a daughter named Linnaea, and it should be, in a way of thinking, a six-letter word (Linnæa) rather than seven. That's more important for calligraphers than for anyone else.
For men's names one medieval and still rare name is Elvis (once Ælvis). Others still around are Albert and Edward (Ælbert and Ædward, back in the day).
A living language changes, and English is one of the liveliest and changingest languages of them all.
Here are some ways my SCA name has been written down: OH WAIT!! I posted this too early. I'm sorry. If you care, check back. Or look through scrolls here. I intend to cut and paste just the names from some of them, but it's going to take some photo manipulation time. http://sandradodd.com/duckford/award/scorpion