As WP Theme developer , here is some plugins which you must know for develop your creativity on theme
- Simple Page Sidebar : This plugin is to show multiple sidebar on your page or post. It’s easy to add or delete custom page sidebar.
- Custom Category Templates : Use this to choose Category Template (just like Page Template). If you want to make the category is different layout, just use this template
- WP Custom Post Template : You can use Post template on your post (just like Page Template)
- Event Manager : just make sure your theme support event manager , because based on my experience many user who use this plugin.
- WPML : WordPress multilingual Plugin. You can translate any page/post on your blog
- RTL Tester : just use RTL Tester to make sure your theme support RTL. Don’t forget theme to support RTL , you can use
- Codestyling Localization : This plugin to generate mo/po for your theme for easy localization from wordpress admin area. You can translate directly from your wordpress admin area
- Titan Framework : if you want to make admin area for plugins or theme. Just use this framework, It’s easy to use. The lack only it doesn’t support repeater group. But i think it’s powerful enough if you want to make plugin/theme without repeater support
- Redux Framework : This is powerfull wordpress admin framework for theme. For metabox support you can use addons
- Theme Check : You can use this plugin to check you theme has passed the test wordpress standard theme or not.
- Update Notifier : If you program premium wptheme which is not hosted in wordpress.org just give notifier with this code http://wplift.com/notify-your-theme-users-about-updates-in-their-dashboard