Steam game gift list (inventory item than can be stored in your steam account) :

Afterfall InSanity Extended Edition
ARMA: Cold War Assault
Bad Rats: the Rats' Revenge
Defy Gravity Extended
Football Manager 2014
Forge - Starter Pack
Ghost Master®
Gun Monkeys
Guns of Icarus Online
METAL SLUG 3
Minion Masters
ORION: Prelude
Pain Train
PAYDAY 2
PixelJunk™ Eden
Real Horror Stories Ultimate Edition
package for red orchestra : Includes 4 items: Red Orchestra: Ostfront 41-45, Mare Nostrum, Darkest Hour: Europe '44-'45, Red Orchestra 2: Heroes of Stalingrad with Rising Storm
Upgrade Red Orchestra 2 Standard to Deluxe
Retro City Rampage™ DX
RIP - Trilogy™
Sang-Froid - Tales of Werewolves
Super Hexagon
Super Sanctum TD
The Ship - 2 Pack Gift
Tiny and Big: Grandpa's Leftovers
Trine Enchanted Edition
Trine 2: Complete Story Gift
Tropico 4
VVVVVV
World of Goo
Yet Another Zombie Defense

Steam inventory for gifts

Humble gifts :-

Kane & Lynch Collection
Lara Croft and the Guardian of Light
World of Goo
One Finger Death Punch
Bridge Project
Universe Sandbox
Operation Flashpoint: Dragon Rising
Operation Flashpoint: Red River
BioShock
BioShock 2
Ballpoint Universe - Infinite
Risen
Tiny & Big in Grandpa's Leftovers
Soulcaster: Part I & II
Hammerwatch
Thomas Was Alone