I thorougly enjoy playing the Milton Bradley game Crack the Case with friends.
For smaller groups (up to 5 people), I find that without teams or keeping track of time or points is already more fun than playing according to the rules. For years, I've played simply by taking turns playing the storyteller. Especially if children are joining in, we'll award the storyteller role to the person who asked the "bingo!" question.
In bigger groups, however, I've found that this style is too chaotic, and I'd prefer to go back to more of a team-based strategy. The conventional rules literally have one team sitting around waiting as only one of the members play the role of storyteller. Does anybody have any suggestions for increasing group engagement while playing in groups of six or more?