These books are promos given away on Free Comic Book Day (usually in May).
Free Comic Book day is an industry-wide event that various publishers use to showcase their comics and talents. Most of these comics are reprints (in whole or in part) of previously (or soon-to-be) published comics.
In the case of the Marvel Comics that appear in this section, the comics showcase Spider-Man. In the case of the non-Marvel comics, Spidey (in some form or another) makes a brief appearance in the comic.
For more information about Free Comic Book Day, go to Free Comic Book Day.