I've got a couple new combos that I think are really fun. One for support and one for sharp.
For support: pump, combat, m32
Great all around loadout (though rather expensive). Pump for general combat, combat for when the pump is either out of ammo or needs to reload, as well as for burst (double tapping husks, clearing out a mob behind a weld, etc.), and the m32 is for hurting the hell out of fleshpounds (don't forget to throw a couple nades before opening up) and distant groups. Scrakes can give you some trouble. Without the coach gun, they're a pain to solo. Still, a competent sharpshooter on your team will fix that. Or if your team is focus firing them, a full clip from the combat is a pretty substantial burst.
For sharpshooter: crossbow, .44, mp5 (currently this combo is weakened by a bug)
The .44 gives you plenty of stopping power for medium zeds, and will be overall your main weapon, using the mp5 for when a group gets too close. You will be amazed at how good the mp5 is with a 50% headshot damage boost. Be careful though, you don't want to get stuck in the long reload with a gorefast eating your face. The crossbow is of course for heavies.
EDIT: The .44 bug was partially fixed, it now gets a reload bonus, though the recoil is still broken. The mp5 was fixed too, sort of. It still fires two bullets every time you pull the trigger, but now it actually shoots both rather than one simply disappearing, so it's not really a big deal anymore.
Unfortunately, this combo is currently quite mediocre due to two huge bugs.
One: the .44 doesn't benefit from the sharpshooters recoil and reload speed bonuses. This makes it a subpar main weapon as you spend far too much time reloading and the recoil makes it hard to double tap important targets like the husk and siren.
Two: the mp5 loses a bullet every time you pull the trigger. You only fire one bullet, but your ammo count goes down by two. This only happens once for each trigger pull, so if you spray the entire magazine at once, you'll lose one bullet. But if you burst fire (like you would as a sharpshooter...) then you'll lose a whole hell of a lot more.
Until these two bugs are fixed, this weapon combo is at best, middle quality. You can use it and make it work, but it won't be anything to write home about. However, I can see a lot of potential in it once those bugs get fixed.