Back on the original subject, I think hex having one or more invocations dedicated to improving it the same way eldritch blast does would not be remiss.

From earlier:
Quote Originally Posted by Segev View Post
Evil Eye
Prerequisite: must know hex.
When you cast hex, you may choose to have your left eye take on a supernatural appearance denoting its vile power. It may have its sclera turn black or crimson, continually drip tears of blood, glow with power, or any other mark of its supernatural charge. If you do, you may cast it without components (though the eye's transformation makes it obvious you're casting a spell) and as if cast from a spell slot one level higher. As long as your evil eye is showing, you may concentrate on other spells or effects while maintaining concentration on hex. If your concentration is broken, it is broken for all things you are concentrating on at once.
There is room for debate over whether it should have a prerequisite level, and/or shouldn't have the +1 slot level. The slot level increase basically moves the 8 hour duration from level 5 to level 3, and the 24 hour duration from level 9 down to level 7. I don't actually see the 24 duration as that big of an upgrade over the 8 hour duration, though I do see the upgrade to 8 hours as pretty big.

Other ideas:

Hexagram
Prerequisite: must know hex.
When you cast hex from a level 1 spell slot, you may target one additional creature. For each spell slot above level 1, you may target one more creature with the spell, to a maximum of six (when cast from a fifth level spell slot). Each creature has the same curse and therefore the same affected ability.

Cursed Blade's Hex
Prerequisite: must know hex; must have Pact of the Blade
Once on each of your turns when you hit a creature with your Pact Blade, you may cast hex on that creature without spending an action. If you are already concentrating on a casting of hex, you may transfer the curse to the creature stricken by your blade without an action, even if the previous victim of the curse is not yet reduced to 0 hp. In either case, the curse is inflicted before damage is rolled for the attack that triggered it.

Bottomless Spite
Prerequisite: must know hex; must be at least 9th level
When you cast hex, you may choose to do so without expending a spell slot. It is not upcast if cast in this fashion.