Excitement, and factorial!
Answer: EBULLIENCE

Each item on the list is a document or piece of text, many of which turn out to have an unusually large number of exclamation points. Count them and convert to the corresponding letter:

ItemNumber of !Letter
the office sign5E
the first of all the #announcement messages2B
the blurb for Error-Correcting Codes21U
the Welcome page of the camper pre-camp form on the appsys12L
Sarah's first proof that e is irrational12L
the Day 1 schedule 9I
the LGBTQ hangout poster5E
Section 1 of Glenn's Crash Course notes14N
the "WET PAINT" sign next to the dining hall entrance3C
the left side of Steve's proclamation that campers won sign-in5E

The answer is EBULLIENCE.