On This Site
POE's Manuals Online
[CPAN's search site] is the best, most up-to-date source for Perl module documentation on the web.
POE Articles Elsewhere
[Building Applications with POE] by Matt Cashner.
[Application Design with POE] by Matt Cashner.
[Doing Many Things at Once] by Randal L. Schwartz
[Watching Log Files] by Randal L. Schwartz.
[Watching Log Files in an IRC channel] by Randal L. Schwartz.
[Graphical Interaction with POE and Tk] by Randal L. Schwartz.
[A Beginner's Introduction to POE] by Dennis Taylor and Geoff Goff. The examples in this article are out of date, however.
Open Source documentation is a work in progress. POE's documentation work has [moved into Git] for better management.
A loosely maintained /Beginners Guide exists. It's full of deep POE lore, and it may be a good guide to conceptual hot spots in the current documentation.