Domain names with high Pagerank are in high demand because a high Pagerank usually means that the domain has many back links from other valuable sites, this can turn in to more traffic or even more PageRank if you 301 redirect that domain.

There are many ways to find domain names with high PageRank, what I usually do is I go to Godaddy and I look under domain names for sale, they usually have a ton of domains listed for sale with high PageRank. If there is a particular domain that you want, you can try a domain backorder domain as well.

Acquiring domains with high PageRank is a good SEO strategy, the search engines value a site depending on the amount and quality of back links and the content of the site, if you have a site in a certain niche and you would like to get a higher PageRank and increase the value of your site finding a domain with lots of quality back links is a must, basically all you would do is you would buy that domain name and you would redirect it through your .htaccess, or even better you can develop an entire site around this domains.

Its up to you, but this helps in both search engine traffic and referral traffic. Now there is one thing that you need to know, most of the time when a domain drops it could lose its PageRank in the next update if the back links that the domain had are removed by the website owners that linked to that site. So its a risk you would have to take if you want to get better SERPS.