A cool list of obsolete skills from days gone by.
Caution:Reviewing these lost skills may induce feelings of old-agedness.

A few skills from the list I've had experience with:
Skill:Entering Freeware Programs From A Magazine Field Computing
Went Obsolete 1988
Made Obsolete By Cheap distribution of software on disk
Knowledge Assumed Touch Typing and extreme attention to detail
When useful This was the mechanism for trying out programs
Also known as a type-in, publications such as Compute! magazine would feature a monthly section that contained the BASIC code or binary data in hexadecimal format for a program which you would then type in to your computer and execute.
Skill:Punching a Hole In The Shell Of A Single-sided 5 1/4 Floppy Disc To Make It Double-sided Field Early personal computer disk drives (particularly the Commodore 1541)
Went Obsolete 1987
Made Obsolete By The widespread availability of double sided drives
Knowledge Assumed Proper alignment and use of a hole punch or notcher
When useful When you didn't want to waste the second side of a disk
Early 5.25" floppy disk drives (such as the Commodore 1541 or Apple's Disk ][) only contained one read head. Thus they could only read one side of a disk. To gain access to the other side of the disk, you had to punch a hole in the corner with either a paper punch or a "notcher" specially designed to line up the hold correctly. Then when the hole was punched you would place the disk upside down in the drive to access the second side.
Something similar was used on 3.5" drives. Punching (or drilling) a hole in a 3.5 made it "high-density" even though it was sold as "double-density" i.e. 1.44M instead of 720K.
Skill:Stacking A Quarter On An Arcade Game To Indicate You Have Next Field Gaming
Went Obsolete Mid-90's saw a major decline in the arcade market
Made Obsolete By Home console market
Knowledge Assumed You need to know how to place a coin flat on a surface or lean it against the glass of the display. You should also be fairly confident in your skill in this particular game. You also need to have the confidence to walk up to an arcade unit right in the middle of someones game and slam down a coin right in front of them.
When useful This skill is still very much useful when it comes to pool or snooker tables in pubs. In England you're especially likely to find a stack of coins across a table with clusters of people awaiting their go. It is also likely that this predates the actual 'obsolete' skill that this is based on.
Field Entertainment
Went Obsolete This is not yet obsolete, just repurposed
Made Obsolete By the playstation
Knowledge Assumed What game you wanted to play
When useful Historically, this skill was used when waiting in line for a game without actually waiting in line. Currently it is used for the same purpose, at pool tables, in bars.
The practice of stacking coins on arcade games is predated by the practice of stacking them on coin-operated pool tables. On the side of the coin slot, it was normal to see a row of quarters and, sometimes, markers (to avoid arguments over who owned which quarter). Markers often were pennies or dimes but could also be just about any other object able to rest on top of a quarter without completely hiding it.
Stacking coins on an arcade game was the defacto way to say 'The next game is mine'. It was also an easy way to reserve a machine for your own exclusive play. By placing a coin on the machine you are effectivly saying 'I have an active interest in playing this and Im going to as soon as its free', this is in contrast to the many viewers that would gather around units to watch with no interest in actually playing. By using the coins you eliminate having to work out who's go is next or who wants to play.
It should be noted that any touching of the coins "whatsoever" was a severe breach of arcade etiquette. It's also not unknown for the current player to get annoyed or put off by an aggressive coin stacking. You are effectivly saying "hurry up and die, I'm up".
Stacking coins on gambling machines is and was also a breach of etiquette. There is an assumption by a lot of gamblers that if they are losing money they are "building up" for a later win. Gambling machine etiquette is to allow the current gambler to continue play until they decide to stop.
This "Skill" may still be observed in bars and poolhalls across the world, perhaps it is the arcade that's obsolete, not the coin placing.
http://obsoleteskills.com/Skills/SkillsRegards,
Sun