What do you to learn something new usually? Google, Wikipedia, then how to get some high-quality resources? I recommend Social Bookmark Site today.
The reason is the links on these social bookmark sites are the resources which people are usually used.
Top 20 Social Bookmarking sites:
10. http://mixx.com
13. http://fark.com
15. http://twine.com
17. http://dzone.com
18. http://faves.com
20. http://diigo.com
D. from http://www.ebizmba.com/articles/social-bookmarking-websites