Originally Posted by smd4

I'll preface this by saying you may already have a lot of these tools in your home tool box (and I see that you do from the post above). Anyway...

--Set of metric open/box end wrenches up to 17mm;
--12" adjustable ("Crescent") wrench;
--Ball-peen hammer;
--Metal shop ruler (to measure chain stretch, etc.);
--Needle-nose pliers (to grab the cable when adjusting derailleur cable tension);
--JIS (Japanese) Phillips head screwdriver, probably No. 2 will cover you in most instances;
--Hex/Allen Tri-wrench in 4, 5, 6 mm;
--Socket Tri-wrench in 8, 9, 10 mm;
--Torx Tri-wrench (I have one but don't use it, because I don't have any Torx fasteners);
--Pedal Wrench (I have an older (Verma?) model that has both 15mm and 1/2" at either end);
--Set of good quality cone wrenches (I use Park);
--High-quality spoke wrench to fit your spoke nipples. Park makes these. Get the kind that looks like a hot-air-balloon with rubber grip. Don't cheap out on this tool!;
--Headset wrench specific to your headset if you use one. Park makes these as well;
--Chain Whip;
--Cassette lockring tool depending on cassette manufacturer (This will be used in conjunction with your chain whip and adjustable wrench);
--Bottom-bracket tools, depending on what you're using and the era;
--Fourth hand (Hozan makes an excellent one);
--Quality bike-cable-specific cable cutters (I use a discontinued Shimano version but the newer Park one seems quite capable);
--Metric Allen key set (the "L" shaped ones);
--Chain Tool (type depending on what you use--rivets, quick links, etc.);
--Tools specific to your bike--I need an extra long 6mm Allen key for my stem and a 8mm Allen for my cranks. I also have a specific tool for my chainring bolts and crank dust caps, and one to adjust my pedal bearings;
--Good quality oil (your choice; I use Tri-Flow);
--Good quality grease (your choice; I use Shimano Special Grease. Phil is good too);
--Good quality floor pump including good-quality chuck for your particular valves (I use a Silca Pista Plus with Hiro chuck for Presta valves);
--Tire valve core tool (I think these would be used if you are tubeless and need to remove the valve core);
--Decent floor stand if your bike can be lifted into one;

Fun tools but completely unnecessary: Angle gauge; digital bike (expensive) or luggage (cheap) scale.

This list is what I can think of off the top of my head, but should be a good start for most home shops. YMMV. There are of course very specialized tools like dropout alignment tools, headset cup and race removers/installers, etc. These can be pricy and not used very often, but many can be fabricated at home. I may add to this list as I think of things.