There are not a lot of outsiders that can fill the "goblin niche". Their naturally high Hit Dice, full BAB and resistances means they're simply more dangerous than a regular old Monstrous Humanoid. Nonetheless, while preparing for a low level adventure, I needed a horde of crawling, creeping, sneaking, biting, spitting, screaming devils to come pouring out of an abyssal portal. This is what I came up with;
Krahling CR 1/2
LE small outsider (devil)
Init +1; Senses Darkvision 60-ft.; Perception +4
AC 12, touch 12, flat-footed 11 (+1 size, +1 dex)
hp 8 (1d10-2)
Fort -2, Ref +2, Will +2
Resistance acid/10, cold/10, fire/10
Immunity fire, poison
Weakness: critical hits
Speed 30 ft.
Melee bite +1 (1d3), 2 claws -1 (1d4)
Ranged spit +2 (1d4 plus phlegm)
Space 5 ft.; Reach 5 ft.
Str 10, Dex 13, Con 7, Int 7, Wis 12, Cha 11
Base Atk +1; CMB 10; CMD 12
Feats Skill Focus (stealth)
Skills Perception +4, Sense Motive +4, Stealth +7, Bluff +4
Languages: Infernal; telepathy 100-ft.
Phlegm (Su): Krahlings spit globules of gross mucas that emits a noxious smell. Creatures hit with this phlegm must succeed on a DC 8 fortitude save or be dazed for 1 round.
See in Darkness (Su): Krahlings can see perfectly in darkness of any kind, even that created by a deeper darkness spell.
Weakness to critical hits (Ex): When an attack against a Krahling is rolled and a natural 20 is the result, the attack kills the Krahling.
Organization solitary, pair, or mob (3-7)