A great example of user created artifacts that I noticed this week is the labeling of a mixing board. Mixing boards allow for different sound sources to be modified then combined to a central output. This is extremely helpful, if you have multiple mike sources on stage and would like to dynamically change their sensitivity throughout a performance or talk.
Although the slider design affords pushing and pulling, it nevertheless looks identical regarding of the input source. Therefore, AV people often will have to hand label each input using tape. This user-created artifact is easy to implement while allowing unlimited flexibility for the next job where the inputs might change.