Whilst one can always use hops, StarSan, a big bag of bottle caps etc it's nice for presents to be something "permanent", and maybe something that is nice to have but you don't completely need - so upgrading things like spoons to stainless steel are a good option for "small" presents.
Books are always good - I like the idea that they're helping the recipient become better at something they love doing. Or can just be interesting. So some random thoughts, whilst we're waiting for Michael Tonsmeire's book on hoppy beer and Lars Marius Garshol's on Scandinavian farmhouse brewing - the former was meant to be imminent, the latter less so :
Anything from Pete Brown, Miracle Brew is probably most relevant
20th Century Pub from Boak and Bailey - they will sign copies on request
Anything from Ron Pattinson if you want to go historical, although printing to order means his physical books ain't cheap
The Brewing Elements series are good but technical, I'd start with Yeast by Jamil Zainasheff and Chris White but then I'm a yeast geek
At a more basic level, CAMRA's Essential Home Brewing includes
these recipes.
Belgian Beer: Tested and Tasted by Miguel Roncoroni and Kevin Verstrepen - putting some science into the analysis of Belgian beers.
Historic German and Austrian Beers for the Home Brewer by Andreas Krennmair (see
this thread)
Inkbirds are always handy - they will have a few quid off via Amazon at the start of next week.
Things like a finishing hydrometer are not one of those things you _need_ but I'm glad I have mine. Can be hard to find in the UK though.
+1 to a 0.01g-capable balance.
Bench cappers are a useful upgrade over twin-lever cappers, for speed and safety but again something you don't _need_.
Yeast ranching stuff - a few Petri dishes, a proper loop, some McCartney tubes etc are also "nice to have" but not essential.
Sorting out your storage - shelving, plastic boxes etc - is dull but makes life so much easier, even a trolley to move your gear around.
Edit: meant to say - hop rhizomes, now-January is the time to plant them.