Oooooooh so here goes.
Carnifex carapace and weapons for hive ships, cruisers and kraken.
Parts from the hive tyrant kit, including weapons both guns and close combat weapons.
The mawloc/trygon kit has soem great parts to make use off too, including the alternate heads and talons.
The devourer as a base and then adding fins with the extended carapace with spike works well.
Here are a few of my blog photos that have my first attempts in and im sure that you will see what I have used, but if not feel free to ask more

This is some escorts, using the deathspitter and the devourers as bases.

Kraken with bits from the mawloc/trygon kit.

Cruisers with the weapons of carinfex/hive tyrant/warriors.

Hive ship, All sorts of stuff here including FOUR carnifex carapace bits...

I have also used a lot of green stuff to pad them out and position them well

I hope this helps in some way.