Page rank of Website

you can try to use these tools
http://www.smartpagerank.com/tools.php

Although stats showing on Alexa are not that accurate, it is still a nice resource. Try Google analytics for more accuracy. Some Cpanel also comes with traffic stats feature, have you tried using it? For your PR, Google Toolbar provides the most accurate rating, simply because PR is by Google. But it does take time before they update it.

If it is for you to track your traffic stats then I find using Awstats and Google analtics the best, you can get all the info you would ever want about your site stats from these.

If it was for looking at a site you dont own, then unfortunatly there is only Alexa traffic rank which is pretty much totally pointless, I say this as it only tracks if the visitor has an Alexa toolbar which 99.9% of internet users dont, or if you add a widget to your site and they click it.

Also it is way to easy to fake Alexa rank for site owners who have an Alexa toolbar if they visit their own website everday then their rank will soon rocket up, even if they have little to no other visitors to the website.

As for PR well you really dont need to worry about it, only thing PR is any good for is if you sell advertising on your site as you can demand more money cos people think high PR means a site a good site, which just aint true just cos a site has high PR does not mean it gets more traffic or better quality traffic to a site, Google PR is just a matter of how Google rate how many and the qualty of the inbound links a site has. Google PR has little to no effect on serps which are what site owners should really care about as its serps that bring traffic not PR.