When I use www.backlinkwatch.com to check some websites' backlinks, I found that they only have around 30 backlinks. How come they can be on the top but without many backlinks?? And why some new websites that are without any backlink can still got PR 1 like mine??
Keep in mind that a lot of backlink measuring tools are only an approximation. Not to mention that those sites you might be referring to probably have better content and are better optimized. And do not pay too much attention to PR. PR does NOT guarantee an increase in traffic. It is just a prestigious rating.
Could be that their on page SEO is pretty slick. Also the quality of the backlinks matter. Two links from high quality authority sites is worth 1000 PR 0 blog comment links. Finally it takes time for backlinks to show up in the backlink checking tools