Originally Posted by jigg

I personally do not like to commit to X-days ad buys, since I dont know if the site's traffic is any good and if it will convert for me and my ads. I much rather run a campaign and target as much or as little and find my conversions and what works that way.

But you can target niches with the other networks too but it's not as obvious. You're either going to have to know who to target (URL), ask your rep for specific sites for your niche, or just run a campaign (and target your niche with keywords where possible) and track here signups come from.