Without Jewish emigration from the Soviet Union, the world would be a very different place. For one thing, this blog wouldn't exist. Here's a very interesting article on Soviet Jewish emigration in the early 1970s, when it became a mass movement. Among other things, the stereotype of the typical emigre as a well-educated Muscovite or Leningradnik is wrong; few of the early emigrants had advanced degrees, and they disproportionately came from the fringes of the USSR, where Soviet repression was both less consistent and more recent.
Early Soviet Jewish Emigration: