We roll all of our own ads, from industry related vendors. The Siropu Ads Manager add-on manages selling the ads, and lets the vendors pay, upload, and monitor their clicks and impressions. It lets them know when it is time to renew, too. I set up a special usergroup for vendors who are authorized to buy them. It shows them at the top and bottom of each page with a 728x90 ad, randomly displayed from the pool of current sponsors. Most of them buy a 2 year contract, but it can also sell monthly or annually (for a higher rate). No intrusive google ads or tracking ads that give antivirus warnings and turn folks away. It presents any new ads for our approval, before it (automatically) invoices them and takes payment.
We also use Siropu Ads Manager for some other things, like random holiday ads that pop up over the sidebar, marketing for potential advertisers, reminders in certain specific forums when someone goes to POST (for sale, make sure you include price, location, etc), special banner at bottom of sidebar thanking donors that mention the type of package they picked, a banner on top of the donation screen that explains benefits, a "happy birthday" banner on top of sidebar when it is their birthday, banners specific to unregistered guests to motivate them to register and unlock more subforums, etc
The forums also accept donations from members directly, using the Xenforo built in UPGRADES feature. I added an option on the top menu, that takes them to pick from several donation options. (1 year, 3 years, lifetime, etc) When they are a donor, I have it put a special donor icon on their posts, give them additional edit time for new posts, editable xenforo (sub) title field on posts, and an increased signature field size.
This is how I fund my Xenforo forums.
