Most of these guys have been around for a while and have been writing constantly about very popular topics. To get a clue what people are searching for you might want to check out technorati´s top search terms or other keyword rankings. And they probably have been posting a lot in forums and discussion groups, thereby amassing a huge amount of back links. Back links are one of the most important factors in getting a high page rank, so your blog will show on one of the first pages of the search results.