Ian Dunn

The <a href="https://wordpress.org/themes/p2" rel="ugc">P2</a> theme lets you quickly create posts from the front end, but by default it only allows you to tag them. This plugin lets adds a dropdown box to the post form so that you can also assign a category to the post.

P2 New Post Categories

Works nicely even on the "Mercury" child theme for P2 :)

Works!

Adds a dropdown menu of categories to the P2 new post form.

Annika Backstrom

The “Who’s Online” sidebar widget shows a list of recently-active 
blog users. It has been built with Automattic’s <a href="http://p2theme.com/" rel="nofollow ugc">P2 
theme</a> in mind, but does not depend on P2 
functionality.
The most recently active users bubble up to the top. After one week, 
users fall off the bottom of the list and are hidden until they return. 
As of this writing the list does not support live sorting; the user 
order is fixed, and users missing from the list due to inactivity will 
be added to the top if they come online.

Works as expected

Who's reading your P2 blog right now? Keep track.

P2 New Post Categories vs Who's Online