If you need better control of ads on your sites you can install and use Revive Ad Server (formerly known as OpenX, formerly known as phpAdsNew...). Since Revive (OpenX) can be a resource hog it's considered a good practice to run it on a separate server so it doesn't affect the performance of your site.
For my adserver I used $5/month
DigitalOcean VPS + Ubuntu + nginx + mysql (LEMP) + Revive AdServer + GeoIP module and it works just great! Ads are served quick and Revive admin is super fast!
Here are some screenshots:
This month stats
Last month stats
Today's hourly stats
Stats per site
Stats advertiser
DigitalOcean VPS is perfectly stable and the load is really low. It could take much more traffic than this:
DigitalOcean load in past 24h
DigitalOcean load in past month
DigitalOcean load in past year
This setup can be useful for rotating ads on your sites and for GeoTargeting specific ads to specific countries or regions. Also you can use this to sell ads on your site and have the full stats so advertisers can track the performance of their ads etc...
If anyone is interested in a setup like this feel free to contact me:
celebempire /at/ gmail