It's never easy to watch people leave a service you've created online. Surely, it's worth trying to figure out why people have decided to leave so you can try to serve remaining users better and potential win back those who've left. But that doesn't justifying requiring people leaving your service to explain why they're leaving: Find a better way to gather then information you need to make your service valuable.
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Book of the Month: New Rules of Marketing and PR - David's Reading of the Audio version is excellent
Gadget of the Month: Canon SD880IS Digital Camera
Web Site of the Month: Google Docs - Used to Write Technology Evangelist Posts