Without Stannis, Renly wins the throne with ease early on, Tyrion never saves King's Landing and proves his tactical skill, and Mance's army defeats the Night's Watch. So yeah, you could say Stannis was important to the whole plot.

[quote]Did Stannis have any sort of impact on the world of GoT besides serving as a way for Melisandre to be in the right place at the right time to revive Jon Snow? .... Did Stannis actually have any significance to the realm or was his story just a dramatic but dead end arc? [/quote] In the show Stannis shapes much of what happens. Stannis, is whom Ned views as the legal next in line for the Throne, as such he informs Stannis that Robert is [b][u]NOT[/u][/b] the father. That beings the "war" in which everything goes to shit. Stannis also introduces his daughter who was cured from grayscale(?), she informs Sam of this and Sam knowing this may be important at some point...perhaps in regards to Captain Friend Zone. Curing him, would almost certainly make it easier for Jon and Danny to be allies, but this is pure speculation. Stannis kills Renly(sp?) who, with the Tyrells probably would have won. Stannis attacks Kingslanding, which raises Tyrion's stock. After the battle Tyrion is a proven and respected commander (even tho his dad doesn't give 2 shits). Stannis introduces the viewer to the Iron Bank. Tho what role the Bank will play in the end is still to be seen. Stannis also puts the Kaibash on the Wildlings army, saving the Wall and the North. Stannis also places Jon in a position where the Wildlings respect him by burning Mance, forcing Jon to kill him. Stannis also solidifies Brianne as being an extremely noble and awesome solider.

He saved the Wall.

I don't understand anything anyone is saying here but show talking is always cool.

[quote]Did Stannis have any sort of impact on the world of GoT besides serving as a way for Melisandre to be in the right place at the right time to revive Jon Snow? There was so much time devoted to him on the show, all for his story to end in a rather dismal and seemingly rushed way. I get that he was the reason Mance Rayder died, but I'm not sure a whole lot would have changed if that hadn't happened. Did Stannis actually have any significance to the realm or was his story just a dramatic but dead end arc?[/quote] I feel Stannis had quite an important role in the Game of Thrones universe. If you go back to beginning, melisandre and Stannis were responsible for killing Renly, right in front of Brienne's eyes no less. This one death causes a fracture with the Tyrell's and forces Margarery to marry Jeoffrey. Stannis also was responsible for the Battle of Blackwater, a battle that brought to light wildfire. As you know , it made a return journey his season but without it being used in the first place, the idea might have eluded cersei. It also was important for Stannis to attack winterfell. Yes he did not win, but his forces drastically weakened the defenses. As you pointed out, this was important to get melisandre to meet up with Jon snow. And that's where his crowning achievement comes into place. Stannis was never in line for the crown. Stannis was always consumed by the "light" ,which ironically uses dark methods to achieve desired effects. This portrayal through the years has set up a true "Fire and Ice" narrative that will be played out during the final two seasons. The ice being Jon snow backed by a cold, dark presence (melisandre ) vs the fire(don't have to explain this one).

Not only did he deliver Melisandra to Jon Snow but also Davos (who is a fantastic character). Melisandra convinced Stannis that he was the "one" but was wrong, ultimately leading him to his demise.

If you hadn't noticed by that point, George RR Martin likes to subvert expectations and end storylines without wrapping them up necessarily, as real life would do.