A few days ago I added the AddThis Drupal module to the site to make easy for you to disseminate the portal contents you find interesting.
This module can be configured to select the sharing services to appear in the first place when hovering over the button. I was going to do that but then I realized that I didn’t know which ones TO choose among the MORE than 300 services available.
Myself, I ONLY use twitter, dzone AND reddit. AND you, what services do you frequently use? Do you use ANY sharing service AT ALL?
Even if the REAL impact OF these services IS limited (IN the sense that many OF the visitors do NOT return, see Comparing the effect OF Dzone, stumbleupon, digg, reddit AND delicious IN the portal ), it´s still much better than nothing!