Re: the hand ones-
They're great for burying threads.
When I used one to sew on the binding, I kept jabbing myself with the points at the top. It didn't work well for me. But that could just be me.
But for burying....makes a long a tedious process go very quickly.
There is also the Spiral Eye needle. More moola, but also great for burying. I don't think I'd sew with these. They don't really come in small enough size for that (at least not for me).
http://www.spiraleyeneedles.com/
Now that I think of it, it's probably great for needlepoint, crewel work or hand embroidery work. I'll keep it in mind when I get back to my crazy quilt project.
I haven't seen the machine ones yet.
Where is the slot - on the side by the eye?
Never mind - from the ad:
>>This is a universal needle with a small slip-in threading slot in the eye to make threading effortless. Commonly referred to as self-threading needles.