Order of Importance

In a flat sturcture without hierarchy, the most effective approach for organizing content might be by the order of its importance. Because learners usually pay the most attention to the beginning and end of a topic, you have quite a few options for arranging the content.

Simple to Complex

Instructional content can be organized from the simple to complex even when the simpler content is not subordinate or prerequisite to the complex content. This strategy provides a slow initiation into a subject, building the learner's confidence and knowledge base.

Alphabetical

Most people learn to use alphabetical order in childhood, therefore it is almost intuitive. Alphabetical order allows for quick and easy accesss to information. My personal favorite organizing tool.

Categorical

When there is no hierarchy, no order of importance, and all of the topics are more or less at the same level of difficulty with no prerequisites. In this case you can organize by category. Example: Colors Orange, Yellow, Green, Blue, Pink, Purple

Inspiration

Check out these sites for more information.

The eLearning Coach
The eLearning Coach is where I share actionable strategies, practical content, product reviews and resources to help you design, develop and understand online learning.
Usabilla Blog
Usabilla helps brands like HP, Philips, Booking.com, Lufthansa, KLM, Transavia and The Economist to improve the performance of their websites, apps and emails with live user feedback. Our clients utilize our software to stop guessing what users want, and start listening to what they need.
Smashing Magazine
Founded in September 2006 in Germany, Smashing Magazine delivers reliable, useful, but most importantly practical articles to web designers and developers.