Some things all shops need, some have been listed, some not.
Good bench vise
Good hack saw, yes their are crappy ones! Lenox and Sandivik are the two I have.
Set of various files, different sizes, shapes and types
Clamps, any kind you can find and as many as you can afford
Sharpie type markers
Small mirror, one on a stick helps
Good flashlight, ( I like the new smaller ones that you can adjust the light output)
Good carbide scriber for layout
Set of Starrett or similar center punches
Starrett pin punches, (Ive owned other brands, love the quality of Starrett)
File card
Number drill set
Spill proof containers, one WD40, one Rapid Tap, one Way oil
Acid brushes, Chip brushes
Good set of allen wrenches, SAE and Metric
Course, Med, Fine diamond hones for tool bits
3" and 6" Starrett dividers
Noga type rotary debur tool
Triangle scraper
4 oz & 8 oz ball pein hammers
Small dead blow ball pein hammer
8oz interchangeable head hammer
12" combination square set
6" scale (I like inch/metric black ones) and I bet I have 6 in the shop, one always in my apron pocket
I could go on but in terms of tools I use all the time that maybe one would not consider "machinist tools" these would be on my list of got to have. Many of these items are things that were on the list when I started my apprenticeship or were things I found myself borrowing often so I got my own very early on. I remember those days, getting paid on Thursday and either saving some $ for a tool or going and getting tools. It was an exciting time. I think Ive bored my wife several times when she has asked, "whats that ?" and she got a story of when I bought it and why I had to have it 40 years ago.