Until recently, promoting Premium plugins was not an easy task. While new theme shops appear every month, paid plugin services are not so common. Things might change though: a new service was launched today, called WP App Store.
If you are using GitHub, here is a big list of all projects you can start watching and forking now! WordPress-Related Projects to Watch on GitHub | Themergency.
http://yoast.com/blog-headings-structure/ A good read on how to organize your heading structure on your blog. h1, h2, h3, h4. You know they are useful, but here is how to make them really useful for the search engines.
Into Plugins? You Will Love This. three persons, carefully handpicked among all the three most important people in WordPress, are writing a book, I mean, THE book, on WordPress Plugin Development. These three fine chaps are Brad Williams, Justin Tadlock and Ozh.