Support pages which just increases the last number of the url
There are many comics which Comic Rocket fails to parse, (only shows the first two pages). Most of these actually use a predictable pattern in the URL. Simply: the last number increases by one for each strip. The last page is determined as where the next page gives a non-"200 OK" response.
Oops. That was apparently a bad example, since the site gives a "200 OK" with just a blank page if you give it a too large number. :/ http://www.mspaintadventures.com/?s=4&p=020219
Another example: http://agc.deskslave.org/comic_viewer.html?goNumber=1
... which also has the same problem.
Another possible solution is to detect when the response is identical between two pages. That works for AnotherGamingComic, but not for MsPaintAdventures. And it's a bit to fragile anyways. There needs to be a robust stopping criterion so we don't go into an infinite loop.
I guess the idea wasn't so great after all. :( I'm posting it anyways for future reference.
Andreas Källberg commented