Running a Wordpress blog...?

Here is some plugins I ran a cross that might help:

Mad Mimi for WordPress
http://wordpress.org/extend/plugins/mad-mimi/
This plugin adds a newsletter signup form to your website
in the content and the sidebar of your site.
This plugin requires a Mad Mimi account.
http://bit.ly/mad-mimi

BuddyPress
http://wordpress.org/extend/plugins/buddypress/
Social networking in a box.
Build a social network for your company, school, sports team
or niche community all based on the power and flexibility of WordPress.
BuddyPress will let users register on your site and start creating profiles,
posting messages, making connections, creating
and interacting in groups and much more.
Who's Using BuddyPress?
More and more WordPress with BuddyPress powered sites are popping up.
You can take a look at some of the best sites
on the BuddyPress demo page or the BuddyPress section of the WordPress showcase.

You'll need some BuddyPress ready templates too.

Great to keep in touch with your blogreaders, maybe...?

WP Avoid Slow
http://wordpress.org/extend/plugins/wp-avoid-slow/
Web pages are becoming increasingly complex with more scripts,
style sheets, images, and Flash on them.
A first-time visit to a page may require several HTTP requests
to load all the components.
By using Expires headers these components become cacheable,
which avoids unnecessary HTTP requests on subsequent page views.
Expires headers are most often associated with images,
but they can and should be used on all page components
including scripts, style sheets, and Flash.
Using WP Avoid Slow reduces number of HTTP requests
affecting the page load performance.

Smart Youtube
http://wordpress.org/extend/plugins/smart-youtube/
Smart Youtube is a Wordpress Youtube Plugin that allows you
to easily insert Youtube videos/playlists in your post, comments
and in RSS feed.
The main purpose of the plugin is to correctly embed
youtube videos into your blog post.
The video will be shown in full in your RSS feed as well.
Smart youtube also supports playback of high quality videos,
works on iPhone, produces xHTML valid code (unlike YouTube embed code),
allows you to view videos in fullscreen
and most recently supports YouTube playlists.