Plugin should let you add links while offline

First, let me say that I love LaterLoop. I use the plugin a lot. However, there's one thing that would make it 10x better for me in an instant. My use pattern is that I read a lot of things on the train (I commute 1 1/2 hours each way), when I don't have internet access. So I open a bunch of pages ahead of leaving, and then read them through the ride.

What I would love is a way to store the links that I'd like to follow but can't at the time due to lack of internet access. I envision this as a hotkey followed by a click on the link, which would use some sort of local storage to note the site, and then sync up at a later point when I have net access.

Is this feasible? Easy or difficult to implement? If you think its doable but won't have time for a while I'd love to know that too; I don't have any experience with firefox plugins but I am a programmer so I might take a look.