site name : http://dmoz.org/
The Open Directory Project is the largest, most comprehensive human-edited directory of the Web.
It is constructed and maintained by a vast, global community of volunteer editors.
whenever you want a number of links on a topic, just go to it and have a number of links related to it,
for example, if you want to know some links about operating system,
see the result of the search.
click on specific topic and you will get a large number of links,, you can add some links also, and become a editor.