Before LinkedIn went public, it admitted it needed to do a better job of engaging subscribers (remember when we all had "sleeper" accounts on LinkedIn). This is a challenge many subscription sites have and can make a huge difference in subscriber retention rates. Here is one of LinkedIn initial attempts to remedy that solution -- an email campaign and clever landing page sent to the first 100,000 members (supposedly). The landing page changed every 15 seconds to show another member's story, and ...