Why google indexes the pages of high traffic sites such as digital point,myspace,digg, and other forums and social bookmarking sites so quickly.
May be because at these sites, after every min, lot of new content is added and google love new content
This logic works for me - Consider this : A search engine spiders visit a page and indexes it. After 2 weeks it visits again and the content has changed, so it reindexes the page and sets and decides to revisit more frequently. The spider revisits again after a week, the content has changed again and so the revisit timer is set to a shorter period. A site that changes minute by minute might eventually get a spider visiting many times per day. This continues until the spider does not detect any changes and it then settles down to revisit at that frequency. Constantly changing sites such as this one, or large news sites get revisits most frequently because the content changes frequently and its worthwhile revisiting. Frequent revisits mean more frequent reindexing. I have no proof of this, but it made sense when it was explained to me in this way.
I think it is the page rank, and new contents. Google crawls the homepage more is because the homepage ranks highest, even no new contents updated.
Google generally index those sites very fast those are updated very frequently. and forums and social bookmarking sites are updated every minute as users keep on adding the content. That's why these kind of sites are indexed very frequently...
when ever i added any new content on my blog with in hour blog is indexed by google, but my blog not having any PR.
I have several GPT sites. Some of them get crawled every day but I change the content every day. Most of them get crawled once a week.