Hey guys, after all the sites and guides which are offering just parts of all the availavable codes, I felt like I'll have to put it all together and create something that contains everything that's possible to be activated. Hopefully you'll find this more useful than any of those non-effort sites/guides.

Also note that you can NOT go past 255 keys, since that's an ingame rule. Every key you activate past 255 will be lost!

1.: Register at: https://shift.gearboxsoftware.com/
2.: Link your steam account to your shift account in the shift webpage.
3.: Go ingame, main menu, extras, shift codes, enter shift code.

Here's my list of codes put together by the date 2014.06.24., 99.5% of them should be working just fine, I tried it all myself too! :)

10 golden keys:

C3KJ3-WCZW3-H5TFK-BTB3T-9RKTZ
CB5T3-TCZKT-Z5TX5-33JB3-BWCCT

5 golden keys:

5353T-WRHXT-Z5JRW-333TB-BT5XK
535TJ-3JC6X-KJXCJ-BTBBT-K5WFR
CT5JB-FSTFX-5TF5T-3JJTT-6CF6T
WJW3B-5HBR6-5BXCT-33TJ3-WXT53
WBCTT-XX3RK-HK6TB-TTTTT-B5Z53
KBK3T-3SHFB-ZKTFW-JTJTT-T6CWK
C3KTJ-KHS6B-H5TFW-T3BJ3-6RB9X
5B5TB-XFBX6-WBXWJ-JJ3TJ-9RXZW
CBCB3-SW36X-KJXW3-TTT3J-SFBSB
C35BJ-SRBF6-5TFKB-BBTJT-FSBZK
K3K33-3W9JT-6XJJT-TB3JB-HWZZF
KJKJ3-T396C-RS93J-TJ3BJ-5W3S6
W3CTJ-BFTFR-KJRK3-JJT3J-H6H36
5TKJJ-5THRC-XZZ3J-33J33-TSZSC
WJCBB-SSFFC-XH93J-BJTBT-Z66ZW
CTC3J-KR9H5-WTZ3T-TJ3TB-6SRRJ
5BC33-CRJRF-WB6WB-3TTTB-655ZX
53K3T-JZJX6-WBXKB-BBJJB-SJH3K

3 golden keys:

KBC3J-95WXF-WBSBT-TTJJB-KTC6K
KTK3J-JWT6X-KB65T-3JJ3J-WHBRT
CJ5B3-6TTFF-5365T-TBJBB-SKTCB
KJWB3-6RXRC-CKR5B-H3WB3-WZRF5
WBWJ3-RSFXB-HKBRC-JJTTT-66HC6
CJ5T3-K5TF6-5TRC3-TBTJB-HZ5ZF
WTCBJ-K39R3-SWTRW-TBTJJ-TKB99
CJCJ3-B6XXC-CK6WT-HTWTB-5SSW5
WB53J-KRRXW-5KXCB-STKTT-XC5BR
WB5TT-JFCXX-CBS33-TTTBJ-JJ95B
K3CBT-CRKR6-CB9BT-T3TBJ-595J3
KB53J-RW5XX-539BT-BJT3J-CC55T
5TKTT-T3SFT-Z5T65-JTTJB-B666Z
K3KBT-ZXRXT-HCJXC-3B3JT-XTCXC

2 golden keys:

5BKBB-TXWS5-WX3BB-TBT33-3SHSB

1 golden key:

WTCJ3-SHH3K-KFJT3-JBJ3J-H5965
KJ5BT-FBKSK-KXJ3T-3BTJT-FJX5C
5T5B3-CWJSK-KRTJT-TTJJT-9HW63
WT5TB-XC5ZC-CX3T3-BBT3B-B35WB
KTCJJ-FHZJW-W6JJB-TTBTJ-R9WWJ
CTWTB-JTBW5-KFTTT-JTB33-JTBWB
WTCBB-H5WHC-5F3T3-TBT3T-HR6TJ
WTC3B-Z5ZWC-HW6JT-JJJBJ-9FWXR

Krieg as Scav:
CTKTJ-JSWJF-SCJXK-3TJJ3-RWTKX

Axton Athene Theme Skin:
CJKBJ-3XWTF-HCJ6K-JJB3T-SB35X

Krieg's Loverpalooza Skin:
WTCBJ-FTCXF-5TXCT-3TJ33-TZXW6

Loverpalooza Skins and Gun:
5T53B-6K9KT-Z5B65-BTJJ3-655CZ

Axton Class Mod:
5JKBJ-K9WHW-WBZTJ-T3TTB-TW9HR

Gaige Class Mod:
W3C3B-5JRZC-WJH33-JBJJB-9S6CJ

Zer0 Class Mod:
CBWJ3-S5CJ3-WTTCF-WX333-9STBF

Maya Class Mod:
WJWJ3-FXC33-KT3CR-KR33J-J9B35

Krieg Class Mod:
WTCJT-J653B-C3TKF-5X333-F6JRH

Salvador Class Mod:
WJKBB-KXC3J-5BBCR-5X33J-XZ6RZ

Axton Head "Warrior of Light:
KJKJT-WHBKX-HC9BT-TJBJ3-XJFSJ

Gaige Head "Wayfarer Wizard":
CBKBJ-6ZJW6-HKH3T-B3T33-F5ZRS

Zer0 Head "G0ry Gh0ul":
CT5BB-XTW5X-9CSBT-3BTTJ-FT5X5

Maya Head "Elven Eliminator":
KTC3T-WTW5F-ZCHB3-BT3B3-XJ9WR

Krieg Head "MY EARS ARE RINGING":
CBKBB-ZHJC6-SWHJT-JJ3BB-3CXHS

Salvador Head "he Beast Within":
WBCJJ-33KWR-S5Z33-BJTTB-65WJJ

Luck of the Zaford Skins & Chulainn SMG:
5JWT3-3H5FB-SCBX5-TJ3JB-H5R6X

Humor in BL2?:
KBWJJ-WTXB9-C59J6-WFBTJ-TK6BJ

Pax East Candy Bar Wrapper:
W3WJ3-3JXTT-6RW5T-SB53B-XJBX9

TTAoDK Axton Skin “Natural Twenty":
KTK3J-FR3JS-ZX55B-B3BJ3-HSRB6

TTAoDK Gaige Skin “Summoner Sickness”:
535BB-3R3BZ-HF5K3-JJB33-3BF3J

TTAoDK Zero Skin “The Pandora Chainmail Massacre”:
CTKJ3-9CBJS-9R5WT-JBJ3T-WKXKF

TTAoDK Maya Skin “Her Violent Nature”:
CBCJ3-W5TT9-S65K3-BJJ3B-XHWWC

TTAoDK Krieg Skin “My Fantasies Involve Blood”:
CBKJ3-5FT39-ZRCCT-JTJB3-RFJ5B

TTAoDK Salvador Skin “Bear Naked” (mind that everything should be entered in capitals and straight forward without spaces, but the guide censores the c, j and b combination of letters somehow, so I had to seperate them to be able to give you the correct information):

5J5TT-R C J B S-ZXWCJ-TJ3BJ-TK3FB

SDCC Hyperion Care Package (Expires 8-10-14):
5TKBB-5CRTX-HCBFW-JJJ3T-HTK6C

Here I'm going to put all the codes that are NEW (!), and noone is sure how long they'll be active. I'm just going to post the basic information I find on the web (content, code, expiration date).

Date: Aug 20, 2014
Code: W3WJJ-6WFKX-SW3RK-JJ33B-B99JH
Content: Baby Maker SMG, Love Thumper Shield & 5 Golden Keys
Expiration: unknown

Expiration date is not sure on any of these.

Note, that activating codes are the ONLY legitimate way of obtaining keys. I did hear about the txt editing trick, but I'd recommend staying on the correct way. The legitimately obtained keys should be more than enough to get you through playing campaign on normal mode, I'd even say getting to lvl50. Eventually everyone's going to realize that farming legendaries is the way to get way better than purple loot. Dozens of legendary weapons/shields/mods/relics/grenades (my personal favourite is absolutely the Lyuda) can be legitimately obtained by farming the correct bosses. I wouldn't recommend cheating on any purpose.