I've seen a lot of people stating lately about how sitewide links are no longer very effective on Google, and that 1000 links from the same site is just as good as 1. How about on Yahoo though? I have around 450 backlinks on Yahoo, and probably about 300 of them are from my sig link on another forum which is relevant to my website. I want to know whether it would be worthwhile posting a lot more and perhaps buying sig links off other members on the site.