Live Google PageRank - Matt says a PageRank update is underway and this tool will show you the Google PR of your website across multiple Google Data centers. So if you notice a higher PR in one of the datacenters, it could translate into a good news for you soon.
Google Cache Tool - You probably know that the query cache:abc.com will return when Google last visited the page but Cool Cache tool goes a step further. Enter any URL and the tool will tell when Googlebot visited this and all other pages linking from it. Will also show if any pages aren't in the Google cache.
Visual PageRank - Like WebMaster eyes, you type-in a URL and the tool will show a nice PageRank graphic over each of the hyperlink suggesting the PageRank of the linking pages. Very useful when you want to get an idea about what links on your site enjoy a higher Google PR.
Finally, if you're really serious about SEO and Google search rankings of your blog, do register your site(s) at Google WebMaster Tools.