There are hundreds of Dreamweaver extensions available. I have a number of Dreamweaver extensions that I like to use. They add functionality to Dreamweaver that isn't readily available, and do things that I need to manage my sites. The following are my favorite free Dreamweaver extensions - they all work in Dreamweaver MX. I haven't tested them in other versions.
This tool converts snippets from HomeSite, ColdFusion, and other Macromedia products into Dreamweaver snippets. I use HomeSite a lot, and this was a big help for moving to Dreamweaver.
If you have a frameset, it can be annoying to have your frames busted by search engines and so on. This extension adds the scripts needed to have the framesets rebuilt around main body pages.
If you use a lot of acronyms or abbreviations in your content, it can be really handy to have this extension. It creates the abbr or acronym tags with titles for you.
Changing the case can often be a tedious task. Before I found this extension, I would open up Word and use it to change the case of text I needed converted.
These graphic extensions require Fireworks, but if you have it, it's really easy to create graphical titles and information on your pages.
This photo album is specifically for Dreamweaver MX. It offers two styles of albums, with many many different templates to choose from. Just load in the images and it builds the whole site for you.
If you create a lot of mockups for your design work, you'll want this extension. It populates your pages with 1-5 paragraphs of latin text so that your clients can see what the pages will look like.
Macromedia created a very complex and easy to use course builder extension. It helps you create exams, checks the student's work and even has timers for each question.
Using the title attribute is becoming more and more common, but it's also hard to remember to do when putting in links. This extension searches your document for links and then prompts you for the title text.
If you don't want your pages to be framed by other companies, then you should get this extension. Just put it on the pages you don't want framed, and they will break the frame for you.