An improvement to Wordpress themes is installing a META Description Tag plugin. Currently the Wordpress theme I am using, provided by Derek Punsalan , is optimized for search engines, but there are a few additional things that can still be done as he also describe in the ReadMe file of the theme.
It may happen that [...]

1. jQuery BlockUI Plugin (v2)
The jQuery BlockUI Plugin lets you simulate synchronous behavior when using AJAX, without locking the browser[1]. When activated, it will prevent user activity with the page (or part of the page) until it is deactivated. BlockUI adds elements to the DOM to give it both the appearance and behavior of blocking [...]

WP-PageNavi: Adds a more advanced paging navigation your WordPress blog.
Installation Instruction:

Open wp-content/plugins Folder
Put:
Folder: wp-pagenavi
Activate WP-PageNavi Plugin
Refer To Usage For Further Instructions

Download
Random Redirect: Allows you to create a link to yourblog.example.com/?random which will redirect someone to a random post on your blog, in a StumbleUpon-like fashion. You can also specific in the URL random_post_type or [...]

Google (XML) Sitemaps Generator for WordPress: This plugin generates a XML-Sitemap compliant sitemap of your WordPress blog. This format is supported by Ask.com, Google, YAHOO and MSN Search.
More information what XML-Sitemaps are and how they can help you to get indexed by the major search engines can be found at Sitemaps.org and the searchenginewatch blog.
Dowload [...]

Akismet: Akismet will come with your wordpress installation. Just activate your plugin and you must enter your WordPress.com API key for it to work.
End annoying comment spam: Tired of wasting time managing comment spam on your blog? Try Defensio. You’ll soon wonder how you ever lived without it.
You will need to sign up [...]