I'd like Divine runes, personally. Might as well get some use outta all these dead gods.
Here is a bunch of suggestions that ill add to as I remember:
Runecrafting tool main hand that increases the multiplier. Preferably crafted or charged from Talismans to increase their value. And maybe crafted from Silver Smithing like tiaras? Perhaps upgradeable like Slayer souls to give people a reason to do runecrafting runs.
Merged Rune Pouch. Ability to store rune multiplier items in pouch. Perhaps RC Urns too?
Runecrafting cape leaves a message in the chat when you activate the ability that tells you what the third rune for goldberg is.
Increased value of Talismans by adding more runecrafting based uses.
Necromantic rune multiplier item like the catalitic and elemental ones.
New combination staves for air runes. Im saddened I cant complete my collection.
Ability to upgrade the Elemental staff further, perhaps by combining all combo staves into one.
Upgraded or combined nature and law staves. Perhaps add cosmic and astral staves?
Modernize the Ourania Altar. Ability to upgrade it to make Necro, Combo and Armadyl runes?
Make combination runnecrafting less punitive.
Allow us to charge Elite runecrafting gloves (or perhaps the wiccked hood) with Fists of Guthix rune gloves.
More RC achivs.
Allow us to buy all Runes in a shop in a single button click. Its kinda annoying we have to buy each rune type individdually.
Some great Ideas on here; (and this thread in general) have sent over to Frosch so it doesn't get lost.
I particularly like 'Increased value of Talismans by adding more runecrafting based uses.' But am interested in what sort of uses you'd like to see?