A few of my items I keep in my computer repair/building area.. sorry for the long list, but maybe this will help people out.
Grounding:
Ground monitoring system (alarm enabled)
Antistatic Mat w/ slow drain resistance
Antistatic Wrist Strap w/ slow drain resistance
Ground pin only plug hub for wall outlet
Cleaning:
Isopropyl Alcohol (90%+)
DuPont Freon-TF (spray can)
Ultrasonic cleaner
Metrovac ESD Safe Vacuum
Horsehair detailing brush set w/ wooden handles (ESD safe)
USB rechargeable handheld vacuum (size of a handheld flashlight for small area cleaning)
Q-Tips
Cotton rounds
Microfiber towels
Cotton towels
Acetone
Vinegar
Baking Soda
Magic Eraser
Simple Green
Soldering:
75w temperature adjustable soldering iron w/ sleep function
100w temperature adjustable hot air pencil
Brass sponges
Solder wick
100% lead solder
60/40 and 80/20 leaded solder
RoHS solder (ewww)
High temperature silver solder
Liquid flux
Flux paste
Solder paste
Syringe w/ needle point for fine flux application or under BGA's for reflow
Testing:
True RMS multimeter
Oscilloscope
ISA/PCI/PCIe fault testing card (read boot codes)
EEPROM programmer
Ethernet cable tester
Fiber cable tester
Kill-a-watt meter
Bench power supply w/ various outputs
Computer Hardware Related:
Various known-good computer hardware and peripherals for testing
External USB floppy
External USB CD/DVD/HDDVD/BD drive
External card reader
External hard drive dock
External hard drives
USB flash drives
Hot swap hard drive chassis (IDE, SAS/SATA, SCSI)
Box of data cables for 99% of what I'll ever come across
Gender changers for I/O cables & ports
PS/2 to USB adapters
AT to PS/2 adapters
Audio cable adapters (digital, analog)
Video cable adapters (VGA, DVI, DisplayPort, HDMI)
A supply of analog and digital chips (board repair)
A supply of resistors, capacitors, inductors (board repair)
Surface mount components, through hole components (interface connectors, sockets, pin headers, etc)
Tools:
Screwdriver set with 50+ bits (torx, security bits, philips, flathead, tri-point, allen head, etc)
Wire strippers
Pin crimpers
Side cutters
Wood spudger
Tweezers
Pliers
Dremel
Nibblers
Ruler
Square
Rotary cutting tool and mat
Hole punch
Rivet gun + various size rivets
Drill w/ bits and hole saws
Hack saw + various blades
Multi-arm part holder
USB Microscope
Fine point needles for fixing LGA pins
Chip extractor tools
Misc:
Kapton tape
3M double-sided sticky tape
Thermal paste (conductive, non-conductive, liquid metal)
Thermal pads (various sizes / thicknesses)
Thermal epoxy
Two part epoxy for plastic/metal
Lexan/acrylic scratch removal compound (3 stage kit)
Various grades of sandpaper
Buffing pads
Rubbing compound
Polish
Wax
Primer spray
Various spray paints (for plastic and metal)
Clear coat
Spray adhesive
Zip ties
Zip tie mounts (square)
Latching wire holders (clip, ribbon cable width, latching)
Cable wrap ties (velcro)
Various gauge and color wiring (solid core, stranded, 32ga thru 0ga)
Everything for custom cable sleeving (mesh, paracord, heatshrink - everything in various colors)
Random connectors for making custom length power supply cables, fan cables, etc. (pins, housings)
....and of course 40 volume developer (liquid and gel) for Retr0brite