Following is a creature I created for use in a one-off Egyptian tomb scenario. It is based on a standard Hell Hound and modified to give it the feel of a supernatural desert creature. I think it represents a good example of how a familiar monster can be quickly and easily modified to both make it feel like a part of the milieu in which it appears and to present characters with some unexpected twists. 

Typhonic Hell Hound
Medium Outsider (Evil, Extraplanar, Fire, Earth, Lawful)
Hit Dice: 4d8+4 (22 hp)
Initiative: +5
Speed: 40 ft. (8 squares)
Armor Class: 16 (+1 Dex, +5 natural), touch 11, flat-footed 15
Base Attack/Grapple: +4/+6
Attack: Bite +6 melee (1d8+3)
Full Attack: Bite +6 melee (1d8+3)
Space/Reach: 5 ft./5 ft.
Special Attacks: Breath Weapon
Special Qualities: Darkvision 60 ft., Immunity to Fire, Resistance to Metal and Stone, Scent, Vulnerability to Cold
Saves: Fort +5, Ref +5, Will +4
Abilities: Str 14, Dex 13, Con 13, Int 6, Wis 10, Cha 6
Skills: Hide +13, Jump +13, Listen +7, Move Silently +13, Spot +7, Survival +7*
Feats: Improved Initiative, Run, Track
Environment: Egyptian Hell
Organization: Solitary, pair, or pack (5–12)
Challenge Rating: 4
Treasure: None
Alignment: Always lawful evil
Advancement: 5–8 HD (Medium); 9–12 HD (Large)
Level Adjustment: +3 (cohort)

Typhonic Hell Hounds generally stand almost 5 feet high at the shoulder, weigh about 140 pounds, and have squared-off ears, long, forked tails, and glowing red eyes. Their hides are a mottled patchwork of red, black, and tan, the colors of the desert. Such creatures cannot speak but understand Infernal. They are native to the Egyptian Hell and are sometimes found associated with the temples of various evil deities.

COMBAT
Typhonic Hell Hounds’ natural weapons, as well as any weapons they wield, are treated as evil-aligned and lawful-aligned for the purpose of overcoming damage reduction. Such creatures have hot breath but much less so than normal Hell Hounds and not enough to add damage to their melee attacks.

Breath Weapon (Su): Once every 2d4 rounds, a Typhonic Hell Hound can breath a 15-foot cone of searing, scouring sand that inflicts 3d6 points of damage (Reflex DC 13 half). The save DC is Constitution-based.

Resistance to Metal and Stone (Ex): A Typhonic Hell Hound has damage reduction 5 against damage -- whether physical or magical -- inflicted by metal or stone, including weapons made of these materials.

Skills: Typhonic Hell Hounds have a +5 racial bonus on Hide and Move Silently checks and an additional +4 bonus on Hide checks when in desert, rocky, or fiery conditions. They also receive a +8 racial bonus on Survival checks when tracking by scent, due to their keen sense of smell.