I got one, too, since I'm the QB Community Manager.
It freaked me out because I have never gotten anything but QB mail at this eddress.
I investigated immediately.
It isn't SPAM.
A while back, the company who owns the board added a checkbox to the newsletter signup that says "Receive special offers from partners".
Only users that check this box will receive the offer emails.
You must have checked the box (or left it checked) when you signed up for the QB newsletter emails.
CreativeBug is their first "partner", so this is the first time that they had anything to send out to the list.
The email leads to a sign-up page for Creative Bug.
Being stubborn and tenacious - and wanting to not sign up for anything without checking it out first - I went around the email directly to the site.
http://www.creativebug.com/
I don't use services like theirs so I have no idea how their prices compare to similar sites.
There are unsubscribe instructions at the bottom of that email.
You should be able to prevent future emails from them if you want to.