HTTP redirects are your friend
One of the comics I like to read, Poisoned Minds, dynamically updates the content of the home page when new content is added. At first glance this might seem all well and good. However, when you send someone a link to a particular day’s comic, you end up with a link to the sight its self, not a link to the comic you want them to see. So what happens if the person you are sending the link too looks at it three updates later? What do they see then? Not the comic you wanted them to see.
What I would prefer is for sites to return a 302 temporary redirect to the particular day’s comic. That way you can easily send a link to the comic you are looking at and be confident that when the person you are sending the link to gets around to looking at it, they will see the comic you intended them to see, not the updated page.
Thus, when you visit the site, http://www.poisonedminds.com/, you would get the dynamic 302 redirect to the real page of the current content, http://www.poisonedminds.com/d/20130628.html, that you are looking at.
You might be thinking, “Ya, but that’s what the permanent links are for.”, which he is correct. However, I stipulate, why should a site cause me, the end user / consumer, to go through more work, when the site could very simply utilize existing standards to both 1) make my experience better / more convenient and 2) make the site more compatible other web technologies that would ultimately reduce the load on the site?