Listly by Miles Austin
Add sign-up forms to your WordPress website. Define form layouts by choosing predefined styles or creating your own style based on dozens of options. Live previews of the final project. Include custom-made sign-up forms in popups and define when it will be displayed. Get reports on the sources of registration.
Akismet filters out your comment
and track-back spam for you, so you
can focus on more important things.
Plugin to easily integrate Listly lists to Posts and Pages. Best thing is Google etc sees the list a text and so your whole list can be indexed
Jetpack supercharges your self‑hosted WordPress site with the awesome cloud power of WordPress.com
performs simple but very effective tests on all incoming trackbacks in order to stop trackback spam.
Commons in a Box is a free software package for dynamic collaboration, built on WordPress and BuddyPress.
A lot has been talked about how the "out of the box" Wordpress search functionalities are... well, not the best. Most wordpress developers know it and that´s why we tend to avoid it installing alternative search plugins. Other developers, as they do not need search functionality , simply do not put the search box or icon anywhere, but...