Each day in June you'll get an entry showing you the first appearance of seemingly minor characters, phrases, objects or events that later became notable parts of comic book lore. Not major stuff like "the first appearance of Superman," but rather, "the first time someone said, 'Avengers Assemble!'" or "the first appearance of Batman's giant penny" or "the first appearance of Alfred Pennyworth" or "the first time Spider-Man's face was shown half-Spidey/half-Peter." Stuff like that. Here is an archive of what I've featured so far.
First Appearance of the Daily Bugle
Interestingly enough, the Bugle first appeared in 1962's Fantastic Four #2...
As for the actual offices of the Bugle, we did not actually see them until Amazing Spider-Man #4!
You see, in #2, we see J. Jonah Jameson's office, but it is for Now Magazine, not the Bugle.
In fact, Peter's first gig as a photographer for Jameson was for Now Magazine, not the Daily Bugle.
In 1963's #4, though, we see Spidey visit the Daily Bugle's offices (they're likely the same building, just with a different name on the front of it - a retcon, as it were)...
First Appearance of Arkham Asylum (along with first super-villain to escape)
In 1974's Batman #258, Denny O'Neil introduced Arkham Asylum (a little nod to the fictional city where a lot of H.P. Lovecraft's stories took place). The issue also featured the first member of Batman's Rogues Gallery to escape from the institution...Two-Face!
First person other than Thor or Odin to lift Thor's hammer
This one is a bit of a trick question, as the answer is the Hulk, but only because Thor had Odin lift the magical properties of the hammer in 1965's Journey Into Mystery #112....
The first person other than Thor or Odin to lift the hammer because they were "worthy," was, as you would expect, Beta Ray Bill in 1983's Thor #337...
Feel free to send in ideas for future debuts I should feature here to firstname.lastname@example.org!