It seems that your comments are wide and varied, thanks to all, to me it seems that the strength is in numbers of sisters of the various options using uinits heavy in assault weapons heavy weapons regular squads and jump pack squads, adding in an assasin for good measure. Although there has to be an effective way of using the inquisitor and his henchmen they just look too cool not to be !
There are several ways to use Inquisitors, especially just to look cool!

Just remember this though: Inquisitors and their retinues are paper thin for their price tags. The humble sister's HQ, Elites and Troops and Fast Attack and Heavy Supports and all are leaps and bounds more solid for a much lower price. The Inquisition however, offers a few tricks, and a few bits of wargear, which are extremely useful. They also offer up nasty imperial weapons, like plasma, or a land raider for good measure.
Really though - Cheap Inquisitor setups, going for utility, are the best route I can suggest to take for most people, no matter what really. The next runner up would be a shooting support squad, with dakka weapons--I would suggest mostly to people never to bother with the plasma cannon (which everyone seems to immediately want to take) or multi-meltas.
So here's a cheap, useful Inquisitor, for example:
Inquisitor
-Liber Heresius
-Bolter
Retinue:
Penitent x 2 (to avoid fear of darkness, fury of the ancients, etc)
Familiar x 1
This unit simply provides the liber heresius, and provides a scoring unit for good measure.
Inquisitor Lord
-Liber Heresius
-Psychic Hood
Bolter
Retinue:
Penitent x 2
Familiar x 1
The same thing as above, but more HQ related, for the Leadership to fuel the psychic hood. He's the same thing, but with the Hood for shutting down powers.
Inquisitor (Lord even)
-Liber Heresius; Bolter
Retinue:
Gun Servitor; Heavy Bolter x 2
Penitent x 2
Familiar x 2
Fire support really; though a Daemonhunter Inquisitor is better for this, to get an extra Psycannon on board.
DH Inquisitor (ally)
-Psycannon
-Auspex
Retinue:
Gun Servitors x 3; Heavy Bolters x 3
Sage
Mystics x 3
Anyhow, hopefully that will shed some light for you or give you some ideas

Cheers!