Having been a developer and WordPress site integrator for over a decade, I have used a number of WordPress plugins that can help you out with adding specific features to your site. This list is not inclusive and I’ll likely be adding to it over time. But I wanted to make sure I had my bases covered in the event that you are looking for a specific feature for your site.
Similar to the list of WordPress Plugins, I have a number of WordPress Themes I can recommend based on what you are trying to do with WordPress. Check out this list if you are looking into that.