Online book about visual design for multimedia. The content is a bit old (originally written in 1996), but the principles of layout and color are still relevant.
Wired Campus: Electronic Portfolios: a Path to the Future of Learning - Chronicle.com
Argument for the use of electronic portfolios as a more student-centered assessment of learning
If we truly want to advance from a focus on teaching to a focus on student learning, then a strategy involving something like electronic student portfolios, or ePortfolios, is essential.
On Implementing Web-Based Electronic Portfolios (pdf)
2002 Educause article about using online portfolios. Some of the technical details are dated, but the checklist of "critical factors for successful implementation" is still a good resource
Researching Electronic Portfolios and Learner Engagement (pdf)
Whitepaper on electronic portfolios providing a background on the theory and research. Motivation, engagement, storytelling, and tools are also covered.