A farming build - but I'm not sure where for...

The Ranger

A simple famine ranger with a couple of PvE only skills thrown in for kicks.

Skills
Famine (Wilderness Survival, Elite)
Edge of Extinction (Beast Mastery)
Brambles (Wilderness Survival)
Quickening Zephyr (Wilderness Survival)
Serpent's Quickness (Wilderness Survival)
"You Move Like A Dwarf" (Norn Title Track: PvE only)
Ebon Vanguard Assassin Support (Ebon Vanguard Title Track: PvE only)
Rebirth (Protection Prayers)

(Italicised skills are optional)

Attributes
Beast Mastery 8
Expertise 10
Wilderness Survival 12 + x

Equipment
A Wilderness Survival Rune is nice, high energy weapon set.

Use
Maintain spirits at all times. Famine and Quickening Zephyr are key. Use Serpent's Quickness to reduce recharge time.
When the assassin is having trouble with a particular foe, use your PvE only skills.

The Assassin A/Me

Uses energy denial skills to benefit from famine with the much over-used cry of pain for an extra aoe boost.

Skills
Deadly Paradox (deadly arts)
Shadow Form (shadow arts elite)
Ether Nightmare (Friend of the Luxons/Kurzicks Title Track: Mesmer skill. PvE only)
Cry of Pain (Sunspear Title Track: Mesmer skill. PvE only)
Spirit Shackles (Inspiration Magic)
Ether Feast (Inspiration Magic)
Energy Tap (Inspiration Magic)
Spirit of Failure (Inspiration Magic)

Attributes
Deadly Arts 3
Shadow Arts 12 + 1 + 3
Inspiration Magic 12

Equipment
Shadow Arts headpiece
Rune of Superior Shadow Arts
Radiant Armour
One handed weapon with +5 energy, 20% enchanting
Inspiration Magic offhand with +12 energy, HRT 10%

Use
Maintain Shadow Form (using deadly paradox before or soon after casting - with Quickening Zephyr up you will have no trouble maintaining Shadow Form)
Cast Spirit of Failure on a foe in the group you are tanking - melee is preferable but it also works on casters. This will give you a steady stream of +3 energy.
Cast Spirit Shackles on an attacking foe - use ether nightmare, energy tap and ether feast to bring energy down more. Ether Feast is also nice as an emergency self heal and Energy Tap is nice in an energy emergency. Let Famine do its job, but use Cry of Pain for the AoE damage.

Looks like you can use that in many places Rosie
It should be very effective in UW if I read it right, so common use there wouldn't surprise me