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If you mean your home page shows gray on the toolbar - well, there's no tool that's going to grab your "real" PageRank from Google.
If you mean a white PR 0, then you'll only see that go up if you get some strong backlinks from other sites. And even then, you' need to wait until the next PR update AFTER Google indexes those new links.
Can I ask what tool everyone is using to check PR? (Sorry if this is a stupid question.)
I have seen these "one-off" toolbar changes on other sites, too - but they are something Google does outside the general PR exports.