Why does everybosdy create giveaways on "The Binding Of lsaac" ?

Humble Bundle 7

HiB7.

My view on this : Bonus points to spend

and its free now or something ?

its part of the new Humble Bundle pack, its not free

Typically if one, or multiple games are appearing in very substantial quantities then they are part of one of the bundle offers from the humble bundle, indie gala, indie royale or similar.
It is a cheap way to boost your "contribution" based on the normal steam prices rather than the extremely low cost you can get them for during the bundle duration.

Cause Humble Bundle :)

you've been here 5 months and you don't know why?

Every time.

Some people seem to find that posting a new tread is more easy than browsing 1-2 pages of forum.