Had a look round at the main WorldCommunityGrid webpage and was looking to see if WCG did any merchandise like baseball caps or t-shirts etc but does not seem to be anything.
I'm sure there would be people we meet in day-to-day life who might be interested in crunching, but it's not always easy to introduce the subject into casual conversation.
So I'd agree, it's a tad surprising that they don't produce some items that might help to promote WCG/BOINC/Crunching in offline situations.