These are old, but they work and I like them.
1. Displaying WordPress categories in a Horizontal dropdown menu
2. Gravatar for post author
3. Highlight author comments
4. Recent posts from specific category
5. How to create your own tabbed sidebar
6.Sidebar with Dynamic contents
7. How to create thumbnails for each blog post
8 How to create a mobile version of your website or blog
9. Separate Comments from Trackbacks
10. How to move a static HTML website to WordPress
11. How to embed google ad in or before or after your top post
12. Twitter messages on your wordpress blog
13. Display Facebook status on your blog
*Not that I’m fond of it, but people love it..