> I have to admit not ever reading xkcd, having more important things on my Kindle.
It publishes 3 strips a week, plus a what-if from time to time. It's not a book, or anything else which would compete with whatever's on your kindle for your attention, unless you're a very, very slow reader.
The bigger problem is that Friday's comic was number 1168, so if you've only just started reading now you have a lot of catching up to do. Then half way through you'll realise that if you hover the mouse over the picture some additional text pops up so you'll have to go all the way back and start again. Then you need to read the blag to figure out what all the references to cancer are about.
Most of the comics can be fully enjoyed in 30 seconds or less, but some require a bit more effort...
The What-If's come out once a week and also require a bit more attention but there's only a handful of them so far.
 I don't know how to get hover text on my Samsung Galaxy S2... maybe kindle's can't get to it either?