Wildrunner doesn't have rage (in fact, it has less of a claim of being a "rage" than White Dragon Lineage), same thing with the Fist of the Forest, and Frenzied Berserker's Frenzy is something I am looking at for later.
I really want to find things that modify rage, too; the current plan is, for early game at least (and, you know, if I were to be in an E6 game...) would be to be a Druidic Avenger 6 with Ettercap Lodge Berserker, Reckless Rage, and Wolverine's Rage, who wields a Berserking Sword.
I'd get +16 Str and +24 Con upon triggering Wolverine's Rage if I, you know, rage with my normal rage; this includes a nice neat +4 to Will saves.
If I was just going to leave this at E6, I would take 4 extra feats that collectively give you +5 to NA while raging (hey, it offsets my penalty to AC quite nicely!), along with Extra Rage and Extra Wildshape.
However, going Frenzied Berserker would get me to +28 Str and +32 Con when all is said and done...
Another route would be sucking some RHD and LA to become a Were-Badger, for an additional source of rage. Hell, I'll dip Barbarian and grab Frenzy as well (+6 Str, +4 Dex, +8 Con anyone?), to get 6 sources of Rage. That's a neat +48 Con right there, along with a +40 Str if I'm going with Frenzied Berserker.
And then... Khyber's Rage, for an additional +2 to Str, but a -2 to AC, to bring my total AC penalty to (wait for it...) -36, at most, but, hey, that's a +52 Str.
I'll check the Berserk; I shall have ALL THE ANGER!
EDIT: Wait a minute... I just had an evil thought.
Custom CL 5 Bracers that affect you with Blood Frenzy and Rage continuously? They are called out as being identical to rage, except for the differences in the sizes of their bonuses... with just those custom Bracers and the Berserking Sword, I'm looking at a constant +14 Str and +24 Con, along with (effectively) 3/encounter 1 round delay on effects I don't like as an Immediate action. Hell, toss Khyber's Rage on the mess of feats I've already got (Reckless Rage, Ettercap Lodge Berserker, and Mad Foam Rager), and that bonus to Strength jumps up to +20.