Throughout the trilogy, it didn’t really seem like Gandalf really needed or even used his magic to do anything. He mostly relied on battle skills (movie) or providing counsel (book). I remember the books mentioning Gandalf having the third Elven ring of fire. What did he use the ring for? I feel like Gandalf being a wizard really had no impact on the story. Explanations?
Short answer: The ring Gandalf had was used to motivate and encourage men. His job was an indirect one - he had direct orders to not interfere directly.
Long answer: Wait for Qadgop to come by.
It kept his breath minty fresh.
Also, with his study of fire, Gandalf had a dozen spells for frying bacon just right every time. I mean every time, and you know how hard that is.
I also understand Gandalf used his magic as a sort of slimming effect. That really comes in handy sometimes when you have to consort with kings and stuff, looking fit. Who’d listen to a chubby wizard with a red face? Not me.
Last, Gandalf was like the uber-super-sayan at playing cannasta. This guy could kick total butt.
From The Return of the King, Appendix B, in its introduction to the chronology of the Third Age, comes the following text:
from pg.455 of the 1965 Ballantine Books edition, 32nd printing (1972).
Although on the next page Cìrdan is quoted as telling Gandalf that he can use the Ring of Fire to “rekindle hearts in a world that grows chill,” this is a metaphorical phrase. Gandalf actually is seen in the books using the ring on multiple occaisions to do magical things with fire. In The Hobbit, he alights pine cones with magical fire and throws them down on the wargs (wild wolves) that have treed the party in the foothills of the Misty Mountains. He is reportedly able to manufacture marvelous fireworks, and indeed, there are several such described in the story of Bilbo’s farewell party at the beginning of The Fellowship of the Ring. Gandalf lights a faggot of wood during the snowstorm on Caradhras, using words of power, then notes that, if anyone can see, he has “written Galdalf is here in signs all can read from Rivendell to the mouths of Anduin.” Then, again, he uses words of power to create a firestorm in the trees surrounding the Fellowship when attacked by the wargs just west of Moria. Other examples exist of his use of fire powers.
Gandalf, of course, isn’t restricted to such powers. He is a Maia, a lesser angelic spirit, akin to the Valar but of lesser degree. As such, he is the equivalent of Sauron, and of the balrog. He flexes his powers just a bit when he apparently causes lightening to flash above Edoras while trying to convince Thèoden to cast off his malaise. And he sends a stabbing white light upwards at the Nazgûl when Faramir’s incoming company is rescued before the start of the seige of Minas Tirith. I have always thought that the thing that made the fight with the balrog in Moria toughest for Gandalf was that the balrog itself was a fire spirit, thus negating the advantage of much of Gandalf’s power from Narya.
Further insight into the powers, origins, etc. of Gandalf and the rest of the istari can be found in the book Unfinished Tales, by Professor Tolkein.
No, no, no. That was the forté of his evil twin, Goodgulf Greyteeth. 
But at least I was right about the bacon.
Mmm, bacon.
None of those magical tricks have to be credited to using the ring. In fact, no one other than Galadriel and Elrond knew that Gandalf had one of the Three, so using fire powers to say Gandalf is here has nothing to do with his ring.
It’s jsut that I was always so disappointed that the wizard never did anything wizardly. 
You mean like battling a Balrog, coming back from the dead, rallying the troops at Minis Tirith in the face of the utter horror of the fell beasts and the Witch King, and breaking the staff of Saruman in the face of absolute seduction?
You just need to understand the difference between a “Forgotten Realms” wizard and a Tolkien wizard.
Yeah, Elminster is, like, Gandalf’s grandson or something.
Gandalf didn’t come back as much as he was sent back from the dead. That may seem like a quibble, but I think it was an important distinction to JRRT.
Gandalf does seem to use his powers openly against magical or “unnatural” foes – Saruman, the Balrog, the Nazgul, the Wargs – but not against mortals (although he’s not above threatening Sam and Butterbur).
Don’t forget driving Saruman out of King Theoden.
My dear friends, you are all missing the single most important use of Gandalf’s magical powers that we know about.
Gandalf saves his powers for matters of great importance. That’s all.
Like eating big dinners? And bothering Death? 
“Back, foul fiend of Morgoth! Your flame shall… er… hey, where’d you go?”
HELLO.
“Oh. I’m dead, am I?”
THAT WOULD APPEAR TO BE THE CASE.
“I don’t suppose there’s any chance I could go back and… er…”
NO.
“Ah. Yes. Well, you see, the thing is, I’m a Maiar, don’tcherknow, and well, I’m sort of involved in an apocalyptic wossname, end of the world and all that—”
THE WORLD IS NOT ENDING.
“—and if you could—what?”
I WOULD HAVE BEEN INFORMED.
“Yes, I suppose that’s true. Look, this has come at a really awkward time. Can’t you let me talk to someone in charge? I think I can get this all straightened out…”
This made me laugh out loud.
Remember the fundamentals. Gandalf was present at, and participated in, the creation of space and time and the world that is. As such, he had the power of command (to some extent) over reality itself. However, he was deeply enamoured with the Children of Iluvatar (elves and men) so would be naturally hesitant to exercise the power of command in the first place (knowing that the elves were entwined with the creation, while men were outside of destiny). Add on to that the limitations imposed on him along with his physical body, and he wasn’t going to show his strength unless The Music of The Ainur (or the Will of Iluvatar) required it.
However, when he did speak a word of command, even DEATH got down off his high horse (Binky). It’s just that Saruman, the Balrog, and Sauron spoke the same language of command as Gandalf.
Without Gandalf’s wizardly interventions, the quest would have failed many times over. Our heroes would have been eaten by Wargs outside Moria, gotten lost in Moria, Devoured by the Balrog, Rohan would have fallen to Saruman, there would have been no rescue of Minas Tirith from the attack of Mordor, and no army marching on Sauron to distract the dark lord from Frodo.
I always found the “flashy” sort of wizardry rather showy and ostentatious myself, no?
Oh yes. Deus ex wizarda.
Shafts of light vs. Nazgul.
The fireworks.
The elven rings, I would venture to say, were not meant to be flashy in their capabilities.
Just because he didn’t cast magic missile every round doesn’t mean he wasn’t totally rad.
Maybe he only had like 10 mp.
How about the illusion of the white horses in the flood at the Ford? While Elrond brought the flood, Gandalf said added his own little touches to it.