Omni Outliner 3 Pro has many enhanced features, including support for online images, links to external URLs, more flexible options for searching and navigating, and rich formatting options for presentation on screen and in print.
OmniOutliner Professional's new clipping service allows you to select text from other applications and seamlessly store that information in OmniOutliner without actually copying and pasting. It's fast and easy to archive snippets from email, content from web pages, paragraphs from TextEdit, and so on.
OmniOutliner also allows you to capture audio directly into your documents so you can add voice memos, or whatever audio you like. The audio file is embedded in your document along with a notation of the date and time.
Your documents can be saved as templates, which can then be used as starting points for new documents. Templates preserve everything about an outline, including its content, its styles, and its document preferences. Once you've saved a template in your Library folder, you can create new documents using OmniOutliner Professional's File > New From Template command.
