A socket adapter set would be really handy too, so you can use bigger or smaller drives with all the different sizes of sockets.
One of those cool magnetic inner cable routing kits.
How about a chain waxing 'kit'?
I made my own wax for about $25 all-in and I've been able to get over 150 (dry) miles before re-waxing. I have 2 chains and when 1 needs re-waxed, I have the other one ready to go and I just heat up the wax and do the other one at the same time. Drivetrain stays super clean, should make the cassette and chains last a lot longer too. I use a mini crockpot and just agitate the chain in it for several minutes to work the wax into the rollers.
My only gripe is that the mini crockpot takes a full hour to melt the wax, thinking about just getting a small sauce pan from the thrift shop and using that over a camp stove instead.
Digital tyre pressure gauge Those rechargeable portable tyre pumps A set of interesting but useful brushes for washing bikes
Membership/yearly/monthly pass for xxx bike park
The most useful brush I've found for bikes is an automotive wheel cleaning brush. Look for the kind that look like a pine tree, about $15usd and are awesome for getting between the suspension linkage bits and also the wheel hubs.
The crockpot was $5 at the local thrift store and helps me keep the wax mess to my shop as opposed to my (wife's) kitchen
My wish list includes a Topeak mini ratchet set, t-handle style torque wrenches, Abbey Tools T-handle multi tool and maybe a Turbo Levo
I bought an Abbey threaded bb tool. A lot of their stuff is very expensive (or straight up overpriced) but some of it is reasonable, like this tool. The look and workmanship of their stuff is very refined, the bb tool i have is a work of art.
Gigantic hammer. Make it outta old washing machines if you have to. Channel-locks. More = more gooder. More bigger = more-more gooder. Allen head socket extensions. Torx head socket extensions. M12 socket driver - 3/8" at least. AC or inverter welder. (because 99.9% of people suck at welding) Tap and die set. Decent drill bits, for the aforementioned taps. A thousand dollars worth of assorted bolts from Fastenal. Rolling work table with 6+" vice. Rivnut tool, and bits if you build junk often. Park tool bike stand.