SeamGrip is on my Christmas List *every* year as a stocking-stuffer. I go though it like crazy. It goes on the bottom of every pack i use plus is used to coat-over any fabric abrasions, cuts, etc. It's not cheap - thinking around $6 a tube and going up, but well worth it! I've used the McNett SeamGrip for Sil-Nylon and it's not as durable as the 'normal' stuff.
Anyway, if you're looking for something to wear in your sleeping bag as you go to sleep, about any down-booties would do the job (presuming they're adequately filled with insulation).
As an aside, for cold-weather sleeping, one thing i do at night about a half-hour before bed-time is fill my Nalgenes (usually 2x 32oz) up with boiling-hot water, screw the lid on tight, and put it in the foot-box of my sleeping bag. Oh what a joy that is!!! From my less-informed and more "testosterone-charged" youth, I've 2nd degree frost-bit (generally known as frost-nip) my feet several times so now i'm more susceptable to cold toes and must take extra measures to ensure i stay healthy.