I used to work in a homebrew store, so I got a lot of questions like this. Most people ended up buying gift certificates, mainly because they didn't know what gear the recipient already had. Beyond gift cards, my most successful recommendations (success=not returned) included: refractometers, bottle trees, decorative growlers, and mini-keg systems. At the time we did not sell pumps, but that's the best homebrew gift I've ever received.
Good Luck!