Help with building a Barbarian

[Foofer]

So I'm currently playing in a game and have a 8th level Barbarian. With the release of the official game I find my Barbarian significantly changed, and I am unable to do any of the things I was planning to with it. My DM isn't allowing me to re-level my character with any other class levels so I'm stuck with the bastard at least until he gets killed off, so...
I'm trying to make the best out of a horrible situation, but I'm having a hard time trying to figure out a decent build for him.
What I'd like to do is build him in a way that is unique from a fighter, something that ideally only a Barbarian can do, but I can't actually think of anything that a fighter couldn't do better. The reason I'm specificly asking about a build that wouldn't be more effective as a fighter, is because if I'm forced into that it would just make me bitter as hell that I can't re-level my character, so.. something unique, so I at least don't feel like I've wasted all my levels.

21 Str
16 Dex
16 Con
13 Int
10 Wis
10 Cha

Anything you can think of with those stats.. to make him unique. (stats include bonuses from leveling up to 8)

[Krome]

The first thing that comes to mind is Movement. Barbarians are kings of movement.

The Rage Power Swift Foot, plus a Barbarian's normal movement bonus let's a Barbarian cover a lot of space. Combine that with a specific feat build, Power Attack, Cleave, Dodge, Mobility, Spring Attack, the Barbarian masters the battlefield, allowing him to move up to 45 feet (depending upon race and stuff) before and after his attack, and getting to make Power Attack and Cleave in the process. 9th level Great Cleave is available, allowing him to get into a thick mess and out again.

Add in Terrifying Howl, Raging Leaper (not Leper!), Quick Reflexes, No Escape, Mighty Swing, etc depending upon the situation, he can do amazing things.

Can a fighter do these things, sure, sort of, but not to the same degree the Barbarian can.

Both the Barbarian and Fighter share a niche, combat, normally melee combat (thought that is not necessarily true of either). So to differentiate look for the strengths of the Barbarian and build upon those.

I am sure others will find better builds, this is the first thing that came to mind.

[Foofer]

If you take one or two levels of Barbarian you can gain the movement speed and with armor training use it in conjunction with full plate. If you want to be a battlefield control character, a fighter with one level of Barbarian should easily be able to out do a straight Barbarian.
I envisioned a fighter with two barbarian levels, dodge, mobility, spring attack, lunge, step up, combat reflexes, stand still, unexpected strike as your rage power, extra rage so you can go a little longer and.. and you are in a way better situation than a barbarian of the same level.
That's my problem with Barbarian. It seems like the new shadow dancer to me. Take a couple levels for the speed and maybe one useful rage power and then get out.

Edit: I just found out that you can't tumble through attacks of opportunity if you're wearing any armor that hampers your movement. So unless you're wearing light armor your screwed as a Barbarian, but fighters can do it in full plate. Jesus.. just more nails in the coffin of the once useful class.

[Quandary]

Foofer:
Seriously, I think you should check with your doctor to see if you have a case of melodramaticitis.
There seems to be an epidemic of it going around this board :-)

BTW, I'll let you in on a secret: Mithril Medium armor doesn't have any movement penalties.

Anyhow,
If you're converting at 8th level, you will be able to take ONE 8th level Power and 3 others.

I would recommend Unexpected Strike for an 8th level Power:
Making Movement AoO's when someone ENTERS your threat area is just the insane-lateral thinking that will make Fighters' jaws drop. The part about being able to "regardless of whether or not that movement would normally provoke" might also put a hitch in your Tumbling & 5' Stepping Fighter friends' undies.

Clear Mind is a great 8th level power, basically granting a re-roll like Improved Iron Will, but PER RAGE instead of the PER DAY your pathetic Feat-addicted Fighter friend has to get by with. You will definitely want to pick this one up AT SOME POINT (grabbing Iron Will would synergize well with it, but Improved Iron Will offers very little if you have this, though I suppose it would let you re-roll a 2nd time if the Clear Mind re-roll is also bad).
You should also notice that all the "per Rage" powers can be used more than once/encounter if you pick up the Roused Anger Power (that doesn't have-any level requirement, but seems to pay-off more once you have one or more per-rage Powers that would benefit). In fact, if you have an ally who can remove Fatigue/Exhaustion, you don't even need Roused Anger to drop & re-start Rage, though without that Power, removing your Fatigue is definitely a heavy action-tax on such an ally.

Terrifying Howl (requiring Intimidating Glare) is also an 8th level Power that could work well, at least if you plan on working cooperatively with another character who has the Feat Dazzling Display, or another means to cause enemies to become Shaken (Intimidate/Fear effect).

For the others, Knockback, Strength Surge, and Animal Fury seem great choices.
Strength Surge synergizes with both because it ensures your Bullrush will work (and if you roll well, move them back 10'+) as well as combining with Animal Fury's bonus to Grappling. If you do plan on Grappling, you WILL need the Feat Improved Grappling to avoid AoOs, but even without it, an extra Bite attack isn't bad. Oh yeah, Unexpected Strike + Knockback (possibly w/ Strength Surge) is LOVELY when someone/something is charging/moving to attack you but you Bullrush them back 5-15', possibly preventing them from attacking you at all (or preventing a 5' step + Full Attack)- Of course, you don't even need Unexpected Strike for that if you have a Reach advantage. Mix in the Lunge Feat and you're really in business. If you have means to Bullrush (Knockback), Grapple, or Trip as AoO's (meaning you don't provoke them yourself when trying those Maneuvers), that also lets you fill in for about 75% of Stand Still's functionality.

Beyond the Powers I already mentioned, Scent (great vs. Invisible targets) and Mighty Blow are ones I would definitely be interested in taking at a later point. Powerful Blow and Guarded Stance/Rolling Dodge are also ones which start to offer more pay-off as you level higher in Barbarian. Note that the Dodge Feats persist for <CON Bonus> rounds after activating as a Move Action, so with a good CON they will last you most of most fights.

Maybe, just MAYBE, you might want to take some more Barbarian levels, now, I hope.