Yep, I have these on my diving dry suit. Basically it's just the leg carried onto the toes rather than stopping at the ankles.
I wear a pair of these under them in the winter - Fur lined Thinsulate Socks - Reed Chillcheater
and normal socks in the summer.
I find them comfy and so much nicer than latex if I end up with no socks on, which happens often as I also have them on my dry trousers which I'll throw on when required.
They aren't as robust as boots but so much better then socks. I use either Warmer boots or Merrills over them. You will need to look after them, especially when changing as stones will do them no good, but that's what changing / car mats are for.
We've a load of the thermal booties in the dive club for sale at £5 plus postage if you fancied some.........