Things a network technician should carry with them on the job

Consumables:

• Cheap Power strips  (It is amazing the number of times a job gets delayed because there aren't enough outlets handy)
• NE2000 clone network cards -- they are slow, but reliable.  Everyone's network software works with an NE-2000 compatable card, can't say that about anything else.  Great way to find out if a problem is due to software or infrastructure.  I also carry some 3C503 cards, primarily because I got them, although I once found a computer which would not accept any of the three different types of NE2000 clone cards I stuffed in it, but worked fine with the 3C503.  Bizzare.
• (update) PCI network cards.  I'd *love* to have the $$$ on hand to keep a stock of 3C905 cards, but I don't.  I normally stock a few low-end 10/100BASE-T(X) cards, typically with a RealTek chip set.  I've had pretty good luck with them, and they cost me less than $20 each.
• IDE drive cables
• Internal SCSI cables (wide and narrow)
• External SCSI cables (this gets expensive: 25 to Telco (big) 50 pin; big 50 to big 50; HD (sometimes called SCSI-2) 50 to HD 50; HD 50 to big 50, and anything else you can imagine needing.  AND, this hasn't even started on the Wide SCSI!!)
• Wide SCSI cables.  You thought the narrow cables were getting expensive??  Yikes.
• Cheap VGA video cards.  Hate to see a dead server because of a video card.
• Twisted Pair network cable and ends (make sure you have both solid and stranded ends)
• RG-58 Coax (Plenum), and ends  (Update:  I haven't touched coax at a client in over a year.  I've since DOUBLED my billing rates for coax, with the explaination that if $250/hr. causes people to go elsewhere, GREAT.  I'm basicly out of the coax business, and anyone still using it shouldn't be expecting quick repairs anymore, so I will forgive anyone who doesn't wish to carry the stuff.)
• More RG-58 coax ends (I've identifed at least three different sizes of RG-58 cable ends.  I've found a fourth size of RG-58 cable, but I haven't found the ends...Most coax problems are at the ends, it is best if you can replace the ends without replacing the entire string of cable.)
• Cheap CD-ROM drives.  I've been finding "slow" IDE drives for around $35 ea, and occiationally I've found SCSI drives for as little as $15 each.  Have one on hand for "emergency" repairs.
• Friends have reminded me of the wonderous things I have made out of popsicle sticks and a glue gun, and complained that they are not on this list.  O.k., have a large pile of popsicle sticks and a glue gun.
• 99% Isopropyl alcohol.  Wonderful stuff for cleaning.  Also useful to flush water out of computers and other devices that water should not have got into.  99% is hard to find.  70% is most common, but has 30% water, so I don't recommend it.  91% is much better, but you will have to check out a well-stocked drug store for it.  A small but complete drug store near me has 99%, don't know how common it is elsewhere.
• Cotton Swabs.  Typically used with above alcohol
• Cheap 10BASE-T hubs.  I typically carry a 16 port, an 8 port and a 4-5 port hub.  The big one is for emergency replacements.  The smaller ones are for unexpected expansion (I *thought* there was a spare jack here!).  Soon, I'll have to start carrying 100/10BASE-T dual speed hubs.

• End crimping tools, both Coax and Twisted Pair
• Simple cable tester (I've found I can identify virtually all cable failures with a simple continuity tester for twisted pair and a digital ohmmeter for coax.  This is assuming the wiring is installed properly in the first place).
• Good screw drivers.
• Nut drivers.
• Torx wrenches, including T-8, T-10 and T-15 sizes (T-8 very hard to find, but is critical for repairing Compaq servers, and thus, an important tool for a network tech to have on hand.  It is also a good reason to NEVER use a Compaq server, but many people don't know this, and do it anyway, and you gotta fix it when it breaks.)
• Vise-grips, both "regular" and "needle nose".  (useful when you can't find that tiny T-8 Torx wrench).
• Hammer, mostly as a conversation piece ("Whadya use that for?" "Frustration").
• Power drill (the temptation here would be a cordless, but I always find my batteries dead when I need them, so I carry both a cordless and a corded drill), with LONG drill bit and masonary bits, in addition to a general purpose drill bit set, and a hole-saw (get that parallel cable end through the wall).
• Drywall screws...amazing what you can build and mount with those things...  Like duct tape, only more permanent.
• Flashlight.  I've found a six-cell Mag light curiously usefull, really gets the bills paid rapidly.
• Fish tape (used for fishing wire through walls, conduit, and dropped ceilings)
• Straightened clothes hanger (used for fishing wire through holes)
• Electrical tape (normally used only for attaching wire to clothes hanger!)
• A ladder (used rarely, and takes up lots of room, but boy is it a life (and neck) saver when needed.  I use one of those cool folding ladders.  Expensive and heavy, but fits well in the van, and gives lots of flexibility.
• A computer useable as both a network server and workstation, kept in very operational condition (this is critical... the idea is in a "Dead Network", usually a new install or a first time on site situation, you can figure out quickly if it is the server that is down or the workstations are inoperative.  I have used a "lunchbox" computer for this to great effect, but it has to be READY to go, you must be sure that *it* works, even if nothing else in the building does.  It is also nice if it could be an emergency server for your customer should a very bad thing happen to their server.
• Jumper cables.  Has nothing to do with computer repair, but boy do you look good when you jump start a client's (or prospective clients!) car...or your own if you leave the lights on on the truck (boy did I look stupid getting a jump from the client...)
• Business cards...give to the people after you jump start their car 8-)
• Wheeled cart.  Since I don't move lots of stuff often, I keep a folding luggage carrier in the car rather than a full dolly.

• Cable Scanner:  Now, I don't install cabling when I can help it, just in emergencies or very small jobs no one else will take.  I have found cheap ($70-$100) cable continuity checkers do great for twisted pair, assuming you have the right idea when it comes to making the cable, and a digital ohm meter does great for coax.  IF you are doing significant cable installations, or are telling people you are doing "Catagory 5" cable installs you BETTER have a Catagory 5 cable scanner to PROVE you are doing what you say you are.  I don't do this, so I don't feel the need.
• Diagnostic software: The best diagnostics are stored between the ears...no disk will make up for the brain.  Besides, usually if the machine can boot the diagnostic program, it runs it fine.
• Packet sniffer/analyzer:  Most of the people who use these have no idea what they are even looking at.  In 15 years of networking, I could have learned something I didn't know through other means exactly ONCE..and that time, it would have told me nothing more than the wiring was working perfectly, the problem was elsewhere (it turned out to be a defective network card driver).