If you’re looking for a thoughtful gift for the geek in your life with a love of the arcane, I recommend you seek out a copy of Enquire within upon Everything for them. There are plenty on eBay.
First published in 1856, and selling more than a million copies in dozens of editions, it’s one of those classic old reference books that’s rather amusing from our 21st century vantage point. You can get advice on etiquette, preventing cholera, speaking proper (and not like a cockney) and lots of splendidly old-fashioned recipes.
But that’s not really the geek appeal. Sir Tim Berners-Lee (genuflect) cites the book as one of the influences when conceptualising the world wide web.
Totally second your recommendation – it’s wonderful.