1. fluke link runner lrat-2000-kit.  this is a more in depth ethernet test kit and it does everything from testing poe to measuring cable distance and showing shorts/crossed pins/other faults to showing cdp info to tone generation, to port identification, to vlan mapping, to testing ip/dhcp/dns, etc.  the kit i purchased includes 6 of the port identifiers which allow you to easily identify user ports at the patch panel as well as the intellitone probe.  this unit supports both copper and fiber.  it's by far the most expensive item in my kit, but if you can afford it, it's a real time saver.  the only gripe i have about this is that it has a rechargeable battery and the charger is proprietary and isn't easy to transport (bulky and tangly).  i like the rechargeable battery, until i'm in the field with a dead battery and don't  have the charger with me.  at that point, i'd much rather be using aa batteries.  in a perfect world, it would allow you to use either.
   
2. 6' db9-db9 straight through cable - for various devices which use a serial port for configuration
3. db9 male to male adapter
4. db9 null modem adapter
5. cisco rj45 - db9 console cable - i usually keep 2 or 3 of these in my kit in case i lose one
6. cables to go usb to db9 serial adapter - since most modern laptops don't have serial ports these days
7. rj45 couplers - i usually keep 5-10 of these in the kit, you never know when you'll need one (or five)
8. greenlee 25' fish tape - for fishing cables through walls, etc.  i much prefer using cable fish sticks, but unfortunately i haven't been able to find any i like that'll fit in a pelican case.  i have a set of fish sticks that i keep in my office, but they don't typically go anywhere with me unless i know i'm going to need them.
9. pack of gel filled telecom butt connectors - for field splicing of analog communication cables
10. 200-300 rj45 modular connectors - they're relatively small and light so i prefer to have way more than i'll need at once than risk not having enough
11. 25 rj11 modular connectors
    
12. coax toner - for toning coax cables
13. klein coax explorer - same as above, but allows tracing multiple cables at once
14. 3m heavy duty double sided tape - for mounting / organization
15. self adhesive cable tie mounts - for cable mounting / organization
16. assorted zip ties - i typically carry sizes from 4" - 18" and use them for everything.  i just replace them as they get used, i usually end up restocking once or twice a year.
17. bulk velcro - perhaps one of the most important organization tools you can buy.  i like to buy the 15' rolls of 3/4" velcro and use it for cable organization where changes may need to be made in the future.
18. ideal compression f-connector tool for coax - used for terminating coax
19. 50 pack of compression f-connectors
20. ideal 3 stage coax stripper
21. 3", 6" and 8" side cutting pliers
22. fluke 66/110 impact tool
23. fluke cable scissors
24. misc screwdrivers - i usually carry 3 sizes each of slotted and phillips
25. modular screwdriver with a bit set containing hex and security bits
26. greenlee cablecaster - for pulling cable through plenum / drop ceiling spaces
27. 10 each of leviton rj45 / rj11 modular jacks
28. fluke ts19 butt set
29. various alligator clips with short test leads
    
30. modular adapters (banjo) - i have a fluke 4 pin as well as a greenlee 8 pin
31. a handful of 6' cat5e patch cables
32. fluke can wrench - for the ability to open telco network interface cabinets
33. stanley fatmax drywall jab saw
34. a few 1 gang low voltage old work wall brackets
35. aa-powered headlamp - for working in dark places
36. two aa-powered led flashlights - cheap and bright, for working in dark places
37. gaffer's tape - for running cable across carpet / floors without leaving marks when the tape is removed
38. fluke pro3000 tone generator and probe set - i have this functionality in the lrat-2000, but if all you need to do is tone a single cable then breaking that out is often overkill so it's nice to have a quick and simple option
39. rj45 / rj11 ratcheting crimper - i always buy combo crimpers that do both rj45 and rj11 instead of buying separate crimpers so i don't end up without the one that i need
40. ideal cat5e stripper
41. 2 sets of perle ex-s1110 ethernet extenders - these are vdsl modems in disguise that allow you to extend gigabit ethernet over a single pair of copper (like an alarm circuit, or analog phone line) for up to 10,000 feet.

since i periodically have to take this kit with me on the road, i purchased two pelican cases and used the organizers / dividers that are available as accessories from pelican to keep everything organized.  this allows me to easily ship the cases via ups without worrying about anything getting broken, though this is a double edged sword - when ups see a pelican case they seem to assume it's bullet proof and won't handle it as carefully as they would a normal package so the cases tend to get abused.

to make sure my tools stay where they're supposed to be, i put two abus 83/45 brass padlocks on each case.  these are a decent security option in that they're 1) pretty beefy, 2) solid brass (weatherproof) and 3) can be keyed to match your existing schlage or kwikset house or office key so you don't have to carry a special key.  this isn't so much to keep things safe in transit as it is to prevent people from "borrowing" things.  i've had several occurrences of things going missing, even right off the back of a golf cart while working.