Michael Arrington showed on Crunchnotes where his traffic comes from in December 2006
1. google[organic] 391,034
2. (direct)[(none)] 326,796
3. digg.com[referral] 192,774
4. google.com[referral] 78,960
5. news.bbc.co.uk[referral] 46,621
6. netvibes.com[referral] 32,444
7. techmeme.com[referral] 25,561
8. stumbleupon.com[referral] 22,294
9. reddit.com[referral] 22,035
10. my.yahoo.com[referral] 19,643
11. techcrunch.com[referral] 18,869
and Danny Silivan wrote base on this data
Beyond Google: Social Media Engines First, Other Search Engines Second
or the 'kissing cousin's of search
Digg
StumbleUpon
Reddit
Techmeme
Netscape
are the traffic power house that are rapidly becoming the equivalent of major search engines - and publishers or search marketers need to think of harnessing them even before traditional players like Yahoo or MSN.
more
o.k. other sites, with different orientation and traffic might have a quite different order of referers ...
via JD Lasica
Search engine land has a short description about the DNRS's
