There is no need to say that impact factors have largely failed to measure scientific value – even within selected groups (look for the Wikipedia article).
But are there any alternatives to ISI-Thompson? I haven’t found so many, the Hirsch factor, Google Scholar page rank, or Elseviers Scopus. Of course download figures of open access journals help to define popularity. But is this impact?
The latest development are citation management systems like CiteULike or Connotea that require to make all your readings public. Maybe its true what 80-year-old Garfield wrote in the BMJ: “there is no substitute for judgement, quality, and relevance. Impact and other citation measures merely report facts.” So blogs are even more important, yea, yea.