Currently only one effect produces an
emblem in magic: original Elspeth's "Ultimate" ability.
Will we see more emblems in the future (yes, as the article linked above teases future planeswalkers with emblem creating abilities)? What about outside of planeswalkers?
Premonition - U
Sorcery
You get an emblem with "You may look at the top card of your library."Having emblems be linked to Planeswalkers makes sense for now, because the planeswalker uniqueness rule and their fragility limit how often one could activate Elspeth's ultimate anyway, whereas the second copy of an emblematic spell is usually useless (as with the above), though not always:
Raw Emotion - 1GG
Sorcery
You get an emblem with "If a creature you control would deal damage, it deals twice that amount of damage instead."(I don't know if the above is correctly worded to compound with multiples, as I intend it to, but I assume it could be done.)