Paid ads are also an option in link building, as long as the text link or banner ad is not a no-follow one.There are advertising companies ot there offering this service, but I think the best way is to find sites which offer private advertising.

Good article

Hi everyone,
       Google does not like paid linking, it wants websites to achieve natural links and Anchor text must not all be the same on links.

According to me here available very nice information about paid links Ads and for me PPC is very important to have dofollow back links.

I don't think that paid links ads are that much useful.