How about Alchemists Ghosts?

[Darklord Morius]

Seriously, what a Alchemist Ghost can do?

Bombs and extracts are physical, so, what this poor ghost hopes to do to defend itself?

[Avianfoo]

Howl in misery and pain.

Edit: No, really. Look at the ghost (potential) special abilities.

[Darklord Morius]

Yeah, corruption touch is nice, but i think that a warrior ghost is scarier, and at a lower CR.

[ArmouredMonk13]

Make him a Telekinetic Ghost, that controls a skeleton. The skeleton can do the alchemist stuff, and if there isn't a ghost touch weapon or a cleric, he just will not be killed.