Sea to Summit has Sil bags that are more water resistant. Not sure how small they go though. I have used their products canoeing and have been very impressed.
Very few bags are truly waterproof. So much depends on closure and that is a user issue. The only things I think are absolutely waterproof are boxes with rubber rings and mechanical closures. Such are made for electronics, cameras and so on. I refer to the bags I use canoeing as "splash proof" so as not to set expectations too high and as a way to encourage folks to do everything possible to keep their stuff dry. Otherwise, they can get really sloppy with their paddling thinking everything is "waterproof."
Double lining really makes a difference as well. Just my $.02.