Are there any spells (sorceries, instants) that grant emblems? The only way to get an emblem that I've seen so far is for a planeswalker's ability to grant an emblem. I wonder if there is any other spell that can be cast to receive an emblem.
While not strictly speaking emblems, there are non-Planeswalker cards which create effects with durations of "for the rest of the game," which is the original wording for Elspeth, Knight Errant (before she was errataed to have an emblem).
Cyclopean Tomb removes mire counters that it put onto a land each turn for the rest of the game after it leaves the battlefield.
Praetor Counsel gives you no maximum hand size for the rest of the game.
Stigma Lasher prevents a player from gaining life for the rest of the game.
As of today (Dec 24, 2014) there are 18 cards with Oracle wording that gives an emblem. As you can see, they are all Planeswalkers.
(source: this search here - I've cleaned up some un-necessary details for readability)
Name Type Ajani Steadfast Planeswalker — Ajani Dack Fayden Planeswalker — Dack Daretti, Scrap Savant Planeswalker — Daretti Domri Rade Planeswalker — Domri Elspeth, Knight-Errant Planeswalker — Elspeth Elspeth, Sun's Champion Planeswalker — Elspeth Garruk, Apex Predator Planeswalker — Garruk Garruk, Caller of Beasts Planeswalker — Garruk Kiora, the Crashing Wave Planeswalker — Kiora Koth of the Hammer Planeswalker — Koth Liliana of the Dark Realms Planeswalker — Liliana Ob Nixilis of the Black Oath Planeswalker — Nixilis Sarkhan, the Dragonspeaker Planeswalker — Sarkhan Sorin, Lord of Innistrad Planeswalker — Sorin Sorin, Solemn Visitor Planeswalker — Sorin Tamiyo, the Moon Sage Planeswalker — Tamiyo Teferi, Temporal Archmage Planeswalker — Teferi Venser, the Sojourner Planeswalker — Venser
Planeswalkers are the only sources of emblems
Mark Rosewater, the Head Designer for Magic, has said on his Tumblr blog that
We have chosen to make emblems a planeswalker-only thing.
That is one of many answers Mark has given regarding emblems, stretching at least as far back as 2011, and continuing to the present day, where Ascend (which is a "for the rest of the game" mechanic which could have been designed using emblems) has prompted questions about the issue again. All of them say basically the same thing.
WotC could, of course, change this decision and decide to let non-Planeswalker cards create emblems. But they have so far shown no signs of being interested in doing so.
That said, until any cards are printed which interact with emblems in any way, effects which last "for the rest of the game" are functionally equivalent to emblems, and those do exist on a number of different card types. The distinction that makes one of these effects an emblem has far more flavor significance than it does mechanical significance.
Special mention goes to Obsidian Fireheart, the card that held the title for "Greatest Reminder Text" ("The land continues to burn after Obsidian Fireheart has left the battlefield") until the Unstable card Gimme Five stole that title with "Offer high fives. Don't hit people."