Several of these strike me as "concentrate things so your initial offering meets some minimal threshold of value to participants." I think the clearest example of what I mean by that is this:<p><i>Tactic 17: Set a time constraint.
You can actually program excitement into the marketplace with the help of time constraints.<p>Examples: At launch, Tophatter only let people bid between 8-9pm PT. During this hour the marketplace felt crowded.</i><p>I wouldn't frame it as being about <i>feeling crowded.</i> To my mind, limiting the time frame helps ensure that there is a sufficient activity level to be worthwhile for participants.