I'm only a level 21 but I've noticed a lot of movie references. Like Bruce McClane (Bruce Willis and his Die Hard character John McClane ), Mad Mel (Mel Gibson and his Mad Max character Mad Max), The Achievement 1.21 Gigawatts (Back to the Future) The Achievement Can't We Get BEYOND Thunderdome? (Mad Max: Beyond Thunderdome), and the Achievement Master Exploder (might be a reference to once again Mad Max: Beyond Thunderdome). Can anyone find any the I missed?
 
Edit: Oh and Bricks skill tree the is a Master tree and a Blaster tree. which is totally Master Blaster from Mad Max: Beyond Thunderdome.

Pandora-dog Millionaire (Slumdog Millionaire)
There are some who call me...Tim (Monty Python and the Holy Grail)
 
Both achievements.

The majority of the achievement names are pop culture references. 
 
My Brother is an Italian Plumber = Mario Bros. 
And They'll Tell Two Friends = old commercial 
1.21 Gigawatts = Back To The Future 
12 Days of Pandora = Twelve Days of Christmas 
Group LF Healer = MMO games, particularly EQ and WoW 
Rootinest Tootinest Shootinest = Yosemite Sam, old cowboy movies, and more than likely, Woody from Toy Story 
Pandora-dog Millionaire = Slumdog Millionaire 
You're on a boat! = Lonely Island song 
You call this archaeology? = Indiana Jones 
Truly Outrageous = Jem (old animated show...fuck you, I liked that show) 
Can't we go BEYOND Thunderdome = Mad Max Beyond Thunderdome 
There are some who call me...Tim = Monty Python and the Holy Grail 
Master Exploder = Tenacious D song (as well as a possible reference to Master Blaster in Mad Max Beyond Thunderdome)
 
Those are just the ones that I picked up right off the top of my head and can remember.  I'm pretty sure there are others that I can't remember much about, other than the "Ding!" achievements.  I laughed at those, solely because I can't count how many times I've actually said "DING!" when I leveled in a game. 
 
As for characters, there are tons of those as well.  The two prominent ones are Mad Mel (combination of Mel Gibson and Mad Max) as well as Bruce McClane (combination of Bruce Willis and John McClane).  I also laughed when I met Dr. Zed, knowing that the DLC is called The Zombie Island of Dr. Ned. 
 
I'm curious about Fence, though.  That achievement seems oddly named, so I'm sure it's a reference to something.

Can't we go BEYOND Thunderdome is actually an MST3K reference (which, yes, in turn is referring to Mad Max Beyond Thunderdome).

your a fence if you receive stolen goods and sell them on, like in oblivion with the thieves guild.

" your a fence if you receive stolen goods and sell them on, like in oblivion with the thieves guild. "

Arena dudes last name is Durden (Fight Club). 

This kinda sorta reminds me of this thread... 

i skipped reading them, hopefully i can catch these myself.

The Trashy Knoll.  
 
Like the grassy knoll, get it?

The weapon "The Meat Grinder" Which has a note War is in your blood. At first i thought it was a reference to Starship troopers, more meat for the grinder and all that. Im pretty sure its a reference to Rambo 4 though.

Anyone get the shield called Cracked Sash? That's a pretty good reference to Diablo.

Skagzilla- Godzilla
Mothrakk - Mothra of the Godzilla movies
 
both are HNM monsters you get quests for

Heh, another cool one I just remembered - In the Rust Commons West there is a mini boss called Rakkinishu, who was named after one of the first mini bosses in Diablo 2. He was a little blue goblin shaman if I remember correctly. It's not a movie reference, but whatever. 
 
WOW, after just killing him, he dropped a shield called the Cracked Sash! Awesome!

"Heh, another cool one I just remembered - In the Rust Commons West there is a mini boss called Rakkinishu, who was named after one of the first mini bosses in Diablo 2. He was a little blue goblin shaman if I remember correctly. It's not a movie reference, but whatever.  WOW, after just killing him, he dropped a shield called the Cracked Sash! Awesome! "

" The weapon "The Meat Grinder" Which has a note War is in your blood. At first i thought it was a reference to Starship troopers, more meat for the grinder and all that. Im pretty sure its a reference to Rambo 4 though. "

" This kinda sorta reminds me of this thread...  "

There is a named Raak boss (not attached to any quest) that drops a Cracked Sash. Obvious nod to Diablo 2.

" and the Achievement Master Exploder (might be a reference to once again Mad Max: Beyond Thunderdome). "