After a bit of testing at the dummy, this macro it seems to do a nice rotation and using all cooldowns available for a brainless 1 spam button.

Macro might be outdated, please check the forums for up to date macros.

Dungeon macro (attacking behind mobs):

/castsequence 
[stealth]Ravage;reset=target/alt Mangle(Cat Form),Faerie Fire (Feral),null /castsequence reset=target Savage Roar,Rake,Shred,Shred,Shred,Rip,Rake,Shred /cast [nostealth]Prowl /cast Tiger's Fury /cast Berserk /cast Feral Charge(Cat Form)

Macro Explanation:

4.2 Druid - Feral (Cat) Lazy Macro

Farming macro (attacking not behind mobs):

/castsequence [stealth]Pounce;reset=1 Faerie Fire (Feral),null
/castsequence reset=target Mangle(Cat Form),Savage Roar,Rake,Rip,Mangle(Cat Form),Rake,Mangle(Cat Form)
/cast [nostealth]Prowl
/cast Tiger's Fury
/cast Berserk
/cast Feral Charge(Cat Form)

Macro Explanation:

4.2 Druid - Feral (Cat) Lazy Macro

UPDATED June 10, 2011: Revised for a better rotation and added Pounce spell when on Stealth, also stealths if out of combat.

UPDATED July 1, 2011: Added farming version (frontal attack does not lock up).

UPDATED October 2, 2011: Cat dungeon – Pounce was replaced with Ravage, rotations reset on target to prevent any lock up and added a modifier (Alt) to refresh mangle and Faerie Fire. Cat farming – Claw was replaced with Mangle for more damage and normal rotation resets on target to prevent any lock up. Trinkets had to be removed in order to have space to make the macros work properly.