I don't have time to test many betas, or interest in some games where i receive free items for. So I'll share them here.
If you use them reply and state the one(s) you took. Thank you.

Inferno Legend:

Login to your account or create new account at http://il.gamebox.com/. Click “Code”.
Input your gift code and click the Claim button.

Code: 2CE8GBHFHGGBGH8

Might and Magic Duels of Champions online: (This one might be expired not sure)

Go to www.DuelOfChampions.com and press Play Now.
Create your free Uplay account (or login if you already have one).
Download and install the game.
Go to the in-game shop and redeem your code. Have fun!

Code: IGNP-Z7F4-4LPS-4P4E

BlackGoldOnline (Beta):

Go to http://www.blackgoldol.com and click SIGN UP NOW.
Create a Snail account with valid email address.
Redeem the code at http://bg.snailgame.com/activation.
Download the game client and you’re all set.

Beta Key: RBC4CGZTD44E7LKYG84S

Swordsman (beta):

Download and install Arc here.
Log in with your Perfect World account information.
Click on your username in the upper-right corner.
Select Redeem Key and enter in your beta key from above.
That’s it! Swordsman will begin downloading and you’ll be ready
to play as soon as closed beta begins. Stay tuned for any upcoming
announcements on our homepage. We’ll see you in beta!

Beta key: HCH79-K1J-46KY

World of Tanks:

Possible items: a free tank or in-game items: 500 Gold, 3 Days of Premium Time, and a Premium T2LT Tank!

Code: 9BNWR-FSARE-5GBE4-5VDUB

Heroes and Generals:

Exclusive Submachine Gun

Code: G83WFERVF0SRE1LABB

More to come soon...