Radio Times loves us! They're doing s1 and s2 quizzes.
Quiz One: A Study in Pink
Quiz Two: The Blind Banker
Quiz Three: The Great Game
If you have NOT seen 2012 Sherlock, beware s2 spoilers.
Quiz Four: Scandal in Belgravia
Quiz Five: The Hounds of Baskerville
Quiz Six: The Reichenbach Fall
RT also asks: What official Sherlock merchandise would YOU like to see?
Here I think perhaps their research has failed them... as RedBubble, deviantArt, etsy, and other sites are already supplying this need for fans. Being rather weary of the Beeb's slowness on supplying goodies.
The Sheetlock body pillowcase was up for sale not long ago as well -- sorry! it's gone from StorEnvy now, but the tumblr image remains.
That was via the WearSherlock tumblr. 8) If you can't find the Sherlock DVDs, they have them too! If you want SH props and swag, that's your source.
Psst! In case you were wondering, SherLEGO will be voted on come January 2014. Go fandom!!!