Pop-up opt-in form

Is it bad to have a pop up opt-in form with offers something free and then has a feild for e-mail entry or should I have it just on my blog in the sidebar somewhere

 

You are immediately asking them to give you their e-mail address before they even have a chance to look around first.

And some may think it is a bit pushey???

Think about it.

No, not a good idea.

 

I thing better to keep it at the side of your blog.
let me users to choice to opt in or not..