I know our group is here pretty Iron Man specific, but I'm curious as to what everyone's opinions are about what belongs on a list of key Annual issues from any publisher. Feel free to add anything you feel is relevant, but I'd like to keep the list accurate to the hobby as a whole. For example, someone might add Avengers Annual 2001 because that's where Busiek cleans up much of the mess from "The Crossing", but the truth is that book doesn't really belong on an industry wide list that most people care about. Even I would like to add Iron Man Director of SHIELD Annual #1 because that was one of the best books I had read in years as I recall, but even that doesn't really belong on the list.
I'd say that books like this might be on this list:
Superman Annual #10 | 1985
Sought after book with a classic Superman story written by Alan Moore. The story takes place in the fortress of Solitude on Superman's birthday. A visit by Batman, Robin and Wonder Woman is interrupted as a horror tale unfolds as they arrive in the arctic at Superman's home only to enter a quiet, desolate fortress finding Superman immobilized by an alien parasitic plant. Cosmic monster, Mongul appears from the shadows as the mastermind and takes everyone out in an awesome battle while Superman struggles in his mind to break free. The panels following Superman's release are awesome, and show him in rare form, incredibly PO'd about the situation he awakens too. This is seriously an awesome comic book.

Avengers Annual #10 | 1981
First appearance of Rogue. This isn't a tremendously pricey book, but it is an annual with a rare first appearance that mattered. Unarguably, Rogue is a key X-Men character and crosses the line into mainstream character use with her ties to Gambit and Ms. Marvel as well. I'd say this belongs on a list of key annuals.

Captain America Annual #8 | 1986
This is debatable, but I'd guess that most comic collectors know the image that is this classic Mike Zeck cover. This story is definitely fan service as Wolverine's adamantium claws are pitted against Captain America's indestructible shield.

Daredevil | Deadpool Annual 1997
This one is less about the story and more about the scarcity. Deadpool is arguably Marvel's most popular cult-classic character, and generally speaking the print runs on Deadpool books aren't ever very large, but usually sought after. This annual falls into that category and is a great find on a supply and demand basis, as far as I can tell.

Amazing Spider-Man Annual #1 | 1964
I'd say this one is definitely the real deal for a myriad of reasons. First, it's a Silver Age #1 issue from Marvel's flagship character, most collectors who can't afford ASM #1, would hunt this down as an early Silver Age substitute. Secondly, it's a product of the heyday of classic Marvel creators Stan Lee and Steve Ditko, and lastly it's the first appearance of the Sinister Six - one of Marvel's first supervillain teams comprised of Spider-man's most recognizable villains.

Dark Horse Presents Annual 1998
I'd imagine that this particular list wouldn't have very many annuals from Indy publishers. Indy books are rarely comic book keys, let alone a once-a-year indy publication. With that said though, this is the first appearance of Buffy the Vampire Slayer. Not the strongest entry on the list, but still this character is a regular draw for Dark Horse readers and another cult classic through years of the T.V. show and also her regularly published books and comic series.

This is a tough list to generate because annuals are often 2nd thought publications, so to have a truly sought after annual is a bit of an achievement, I'd say. What else can we add to this list and have it stay relevant without straying into speculation books?