If you have ever wanted to dabble in Joomla extension development but don't know where to start, then I have good news for you. Back in January 2013 I released a 12 part online course on Joomla component development, and now I've decided to give you FREE access to this course. Simply sign up at http://training.tamlynsoftware.com and you will gain access to the videos.
Although the videos focus mainly on Joomla 2.5, they also touch on Joomla 3 nearer the end, and most of the code is still relevant.
I hope you find this useful, and let me know how you go.