Almost every human must learn for success in their live and jobs. E-Learning is a way to support the hard learning and training process for people. I've shown some possible example in E-Learning systems and have shown some new ideas on Barcamp Mainz (http://www.barcampmainz.de/). Some Natural Language Processing (NLP) things were told too. In my opinion E-Learning will be the next big step in the Web for better user experience in learning.
Clipping is a handy way to collect important slides you want to go back to later.