This one would be fun to have in a library.
http://www.sheldoncomics.com/archive/021017.html
I've gotta put in a 'second' for the Mr. T "Suckas, Fools & Chumps" strip (http://www.sheldoncomics.com/archive/060920.html) - I've got it printed on my wall to introduce friends to the strip, and would have purchased it by now were I not worried about eating.
http://www.sheldoncomics.com/archive/050728.html
I am shocked it isn't sold yet.
I definitaly have to agree with those that like this one -
http://www.sheldoncomics.com/archive/051219.html
I mean it explains about Sheldon and in one simple comic as well as being very funny. My vote is for it.
It's always hard to choose just one isn't it! My vote(s) go to:
http://www.sheldoncomics.com/archive/081005.html
Almost all of there characters are in the strip and it practically explains the entire idea of "Sheldon"
But Sweet Fancy Moses I've always that this one was hilarious
http://www.sheldoncomics.com/archive/050728.html