So to combine the two, here's something I saw in an infomercial the other day. It's not really a novel idea, but I've been thinking about easy solutions to make my apartment less drafty and cold (we don't have central heating...and it's been getting down into the 40's inside...which isn't a whole lot of fun). It's called the Twin Draft Guard. Basically it's a door snake, but it fits on either side of your door and moves with the door, so you don't have to constantly readjust it. It's very much an "As Seen On TV" thing.
It's not particularly complicated, so I might try making my own makeshift door snake, given that most directions online say it's an easy project for beginning sewers (and I would count myself one).