AC Buffs

[Erock]

In Pathfinder, what ways other than Bracers/Amulets and mystical magical Light armor can help Rogues/Casters without impeding their abilities? Between Dex and Mithral I've gotten my Rogue up to 18, but that'll need to come up.

[Squirrel_Dude]

Rings of Protection are also pretty common AC boosting items.

[Oscredwin]

Ring of Protection +X
Amulet of Natural Armor +X
Gloves of Dex +X
(Mithril) Chain Shirt +X (or bracers of Armor)
(Mithril) Buckler + X

Those are the basics, takes you from 10-14 (depending on Dex) to 38-42. Then you get into defending armor spikes, miss chances, mirror image, alterself/polymorph for more dex/natural armor.

[Feralventas]

You can just not wear armor and go for Bracers of Armor instead, though that will not give as high a bonus on its own.

Dex bonuses have been noted already.

If you're going Oracle of Lore for your mystery, you replace Dex with Cha, so that might count.

If you've got access to them, the Mage Armor and Shield spells alone will bring you up to 18 as a base.

If you're playing a Small race (gnome or halfling are common and core) you get +1 size bonus to AC.

A one level dip in Monk grants Wisdom modifier to AC, and might let you pick up a Monk's Robe for 1 more AC via their unarmored bonus, but you do need to be unarmored.

Defending enhancement on one of your weapons adds the enhancement bonus (minimum 1) to your AC.

[Spore]

Duelists gain INT as well as DEX on their AC, and some cheesing is possible with the dwarven/stalwart defender.