How can I improve a web page's Google PageRank?

Links in help. A lot. Make sure your sites are well indexed, that they have unique content.. Try and get people to blog about you. Post on newsgroups and forums.

Once we did the redesign for Fluther our page rank shot up because people in the blogosphere started to take notice. There are also a bunch of webmaster forums that have helpful tips… though I can’t remember the names off-hand! Sorry!

Optimize your site using Google Webmaster Tools and upload a XML Sitemap (you probably did this, but just in case) . As andrew said inbound links really helps. It gets even better if you can get some of the inbound links from sites with high pageranks. For example, my tumble-log which I started a few months ago increased its pagerank by 1 point after one page made it to digg.com and reddit.com. Don’t forget to have different headers. A lot of the people I work with get say that they get some good help from high rankings forum (but i have personally never used it)

PS. if you surf around some of the forums, you’ll find some black hat techniques to improve your pagerank. If you do so, do not use them. Even though it might help your pagerank go up for a few months, eventually if Google figures out the hack, then your site gets banned from the search or its pagerank goes down to 0