Aery_Soul's hair products are excellent in that respect, all of them.  AprilYSH's Sylphiad Hair is very good at this too.  Dynamic hair can be made to hang upside down quite easily but it requires a LOT of work to set up, pose, simulate, and render, many times more than a typical hair figure or prop.  That's all I can think of although I'm sure there are others.

I am kind of gaga for gonzo flying hair, examples in my gallery (beware the titties though).  I stick to Aery_Soul's ponytail for the most part, and I really like it because it's very organic (can be completely posed by magnets), but I own all of their hair products and every one can be made to do some extraordinarily beautiful things.  Sylphiad Hair is in the same league of power and flexibility.

edit:  it should be noted that many ponytail hairs can hang the tail in pretty much any direction, often the tail is a boned set of joints that can be rotated, bent and translated just like any limb on a body.

My Freebies