A toner and probe is an indispensible tool to a network installer/repair technician. It's so helpful for locating unidentified (unlabled) telephone and network wires. This model is professioinal grade and recommended for anyone who does this work as a trade. There's a more economical model to here.  Also, here's a video that shows how this tool is used.
An Impact tool or aka: Punchdown tool uses a spring-loaded resistance to force wires into place and then (optionally) cut the remainig slack off in the same stroke.
A network field techncian would have this as one of his/her top-5 tools in their arsenal. Here's a video showing the tool being used to terminate a network wires on to a keystone jack.
Electrician Scissors aka "SNIPS"
Electrician scissors (or sometimes called Lineman's snips) are special heavy-duty scissors designed to cut network wires, strip cable jacketing and some other tasks which cannot be performed (easily) with traditional scissors. They can even cut a 50wire telephone cable - try doing that with household scissors!
 "Don't leave home without it". As a very experienced Datacom professional, I've been wearing one of these tools on my belt for over 20 years. On the job I reach for it several times a day. It's like having a mini toolbox with you at all times. Saves a lot of trips down the ladder to grabe a tool.
 A non-LED flashlight is essential. Busy technicians often find themselves working in spots with poor lighting (closets, under desks, storage rooms, network cabinets). Incandescent lights (non-LED) work best because it allows you to see color. LEDs can be useful for some things, but they washout color making it hard to identify color-coded wires and resistors.
 Even though datacom work is mostly centered around small electrical devices, the need to loosen nuts and bolts comes up occasionally as we have to remove access covers, or undo mounting hardware.
 This is great for helping to see behind tight spaces in equipment closets and inside walls.  The most common use of this looking up inside the hollow space inside a wall after you've just cut the retangle whole where your wall jack is goiing to go.
Klein RJ-45/11 crimp tool
Fish Tape
"red-heads" phone splicers
B-connectors
Velcro Cable mgmt
Allen Wrenches
Reversible Screwdriver
Measuring Tape
RJ-45 crimp ends
Surface phone jack
Cable tester
1/4" ratchet set
Fluke Linemans' Test set
Small, portable POE detector
9v Batteries for Testers and Probes
Fluke "Banjo" adapter
Spudger tool
FiberLert by FLUKEnetworks
RJ-45 Ethernet cross-over
Spudger tool