I've just put out the first official release of the reCAPTCHA Drupal Module, which lets you use reCAPTCHA to use an awesome captcha system and protect email addresses. Although it's a pretty simplistic module, I learned a lot in the process of making it.
Making a new module ended up being pretty easy. All you have to do is create your new myModule.module, the myModule.info file, and then stick all of the Drupal hooks in there that you want. For the reCAPTCHA module, I mainly used hook_filter and hook_captcha.
Source control through CVS is a very powerful, and Drupal takes full advantage of it. All Drupal project releases are based on the CVS tags. If you want to make a new release of your module, you just Tag the release in CVS, tell Drupal.org that you tagged a release and it handles the rest for you.
I've come to realize how flexible the Drupal system really is. Drupal is not just a content management system, it's a framework, a system, an API to aid in rapid website development.
Overall, I've learned a lot by putting together this module, and look forward to working on more Drupal projects to learn more about it.