There is a lot of research going in in affective learning. To measure emotions you can either track sensor input, prompt the student for an emotion description, or reason on the student’s general input (via keyboard). A simple way to express emotions is to use emoticons. People using messengers also use emoticons intensively. Why not the same emoticons (for instance from ICQ) in an e-portfolio, or more generally in an e-learning environment. Though, emoticons can lead to distraction, they can also havce some advantages:

• They express in short a motivation state.
• The gesture to express emotions is shorter than typing text.
• Distraction can also have a positive impact: have a break, to bring the brain down.
• Assuming that being in good mood implies being successful, learners will want to show their emotion to fellow students.
• Assuming that being in a bad mood implies being unsuccessful, emoticons can inform others (teachers/fellow students) that help is needed.

Just my five pence thoughts.