Use Twitter to tell people when you update your showcase, send out a newsletter or add information to the watcher tab. Invite watchers to your showcase via twitter regularly. This is all easily done with the twitter features on Showcase Central.

By adding the hashtag # symbol to a word in the tweet describing your showcase you can link your tweet to other search results containing the same word and get exposure beyond your own followers. If enough people are using the same hashtagged word your showcase may become part of a trending topic.