I downloaded the Google toolbar and installed for IE browser. But as per PageRank - Toolbar Help, the PageRank button cannot be found on the Tools tab( Documentation not updated!!)
Then I ignored the Google toolbar and searched on Google for some other different software which let you know the PageRank for the given page. But I could not find any convincing alternative to Google toolbar.
Next day when I was looking at the Toolbar Options, I noticed Privacy vertical tab page next to the General tab page.In that Privacy Tab Page I could found the see option to select the PageRank under the Enhanced features tab.
See below the screenshot which shows how to enable PageRank in google toobar:
|Enabling Google Toolbar's PageRank button|