It's important to note that Google PageRank is not the same thing as link popularity. PR is actually a subset of link popularity. Whereas PR focuses strictly on the quantity and popularity of links, link popularity adds a "quality factor" into the equation. Unfortunately, many people mistakenly use the terms "link popularity" and "PageRank " interchangeably, which has served to confuse the issue further.
All major search engines place some emphasis on link popularity in their ranking algorithms. There appear to be 2 main types of links that work best to increase your link popularity: links from other sites that focus on the same keyword phrases your site focuses on, and links from relevant categories in major directories and industry-specific portals. "Free-for-all" (FFA) sites do not constitute quality links, so don't waste your $24.95 submitting your site to 500 of them. Links from sites that focus on topics that have nothing to do with your site probably won't help you win any link popularity contests, either (although they may temporarily boost your PR).
