If you are a smoker, there's a Zact for you too! And as of this review, it's available via eBay worldwide.
For the rest of us, Zact is not my favorite. This white paste has a very chemically-medicinal taste. However, the pop-off lid is very convenient. If you're in Indonesia you say, "tutup," to describe the sound (or feeling) of the lid popping off.
Though I am a heavy coffee drinker, I did not use enough Zact to report on its stain-relieving qualities. I must say that I was a little scared that the same chemicals that might remove my coffee stains might remove something else that I want to keep. Every single ingredient on the package has a chemical name, except for xanthan gum, a harmless thickener.