Pagerank means several backlink.In short it shows how many quality links your site has got.So to increase page rank we need to increase back link to our website.
One best and fast way to increase pagerank is creating own theme and plugin for wordpress or blogger and releasing it as GNU Free to use license.
What will happen a lots of blog will review your plugin,your theme.As good as plugin or theme you will write the more reviews you will get on various blogs/sites.
Keep homepage of plugin and theme same of which you want to increase pagerank.Best practice is keep your homepage.You will a single backlink from a single blog reviews your theme or plugin.
The trick works perfectly for anyone.I made 4-5 wordpress theme and they had good quality so got huge backlinks.The page I kept raised from PR0 to PR2 within 15 days as PR update was about after 15 days I released my themes.PR2 in 15 days not bad.
Oh you most be thinking how much time did I spend? It was about 10 hours at all.Isn’t it great.
You should try it.For both you will need PHP knowledge.For themes you will need Photoshop,CSS,html knowledge in addition.If you get any doubt in this ask me.
My pagerank was internal.It hardly matters for me.But you can try this trick on your main domain.Remember PR has direct relation with SEO.PR is SEO’s son so SEO takes a lot care of high PR pages.