WP-PageNavi – Adds a more advanced page navigation to WordPress, which is very useful for navigation on index and category pages.
Evermore – Abbreviate all posts when viewed on multiple post pages. Helpful to create expandable posts summaries in WordPress. Combine with Less that changes the (more) link so it displays the entire post, not just the part after the “more”.
Random Redirect – Allows you to create a link to a random post on your blog. Lets readers browse in a StumbleUpon-like fashion.
WP-Cumulus – displays your tags and/or categories in 3D by placing them on a rotating sphere
Homepage Excerpts – Gives flexibility to use both full posts and excerpts on the homepage.
WordPress Mobile Edition – shows an interface designed for a mobile device when visitors come to your site on a mobile device.
Popularity Contest – keeps a count of your post, category and archive views, comments, trackbacks, etc. and uses them to determine which of your posts are most popular.
Clean Archives – designed to display your archive listings in a clean and uniform fashion. It lists the Month / Year, the day of the month the article was published, the title of the article, and the number of comments that have been made on each article.
Custom Query String – set the number of posts (custom queries) for every single page on your website like categories, archives, or search results pages.
KB Advanced RSS Widget – a wordpress widget that gives you complete control over how RSS feeds are parsed for your sidebar.
Permalinks Migration Plugin – safely change your permalink structure without breaking the old links to your website or affecting your search engine rankings.