I am wondering if somebody could recomomend some good weapon combos. Example: SCAR-Holo-Grenade Launcher.

depends how you play tbh.
i usually go with red dot sight and extended mags as i spray a ton of bullets lol

I have a scar and sniper each with attachments

SCAR (which quit working on level change in campaign)
Laser
Holo Red dot
shotgun attach under barrel
silencer
3 shot

Sniper
silencer
scope
single shot

Thanks. I normally play medium range but not a sniper.

Like the scar

Extended Mags and Silencers ARE your best friends....

C4 is fun too especially with Side Pack 2

wat does side pack 2 do?

Side PAck 2: give an extra explosive...

Using the Assault scope (unlike Crysis 1) on any weapon but the sniper rifle, or the Grendel is completely useless. Best to buy something else because every other weapon that can mount the assault scope is inaccurate. I would recommend using the assault scope on the sniper rifle for MP because the maps are so tiny (except the island), that using the sniper rifle is impractical. I was experimenting by the time I mounted the assault scope on the Grendel and it is very accurate and is well worth buying early on. I'm not certain, but it appears that the silencer hurts a weapons damage (similar to C1), atleast it seems that way on the SCARAB. I don't notice it as much on the Feline though. The K-VOLT and L-TAG are useless, at least after the PS3 patch. Seemed like the K-Volt was more powerful in the beginning. The L-TAG is only useful from a distance for bombardment of objective areas. This is because they will only kill someone who is cloaked ("busted"), or if you hit them directly (given they are not in armor mode). Here is a list of my current weapons and attachments (given my playing style - usually more sneaky and cloaked):

New favorite: Grendel - Assault scope, Silencer, Grenade launcher.
Former favorite: SCARAB - red dot, extended magazine, grenade launcher.
Backup weapon (need dual primary add-on): Feline - silencer, extended magazine.
Sniper: DSG-1 - Silencer, Assault Scope.

When I don't feel like sneaking around:

MK60 - Extended Mag, red dot (reflex)
Jackal (less damage than Marshal, but M fires way too slow to be of any use) - extended mag

I like to mix-up weapons - but favourites so far are:
Feline with Silencer, Reflex, Extended Mag
Scar with Reflex, Extended Mag (?)

Not played with the latest balance patch - due to PSN being down.