AdPlugg

AdPlugg serves and reports on ads you sold yourself, with a WordPress plugin for sites that live there and tags for everything else. The free tier runs a hundred thousand impressions a month, which covers a small site outright. Above that the monthly fee is small and the real cost is metered per thousand impressions, published as a table rather than quoted. Nobody here is finding you advertisers.

Three published plans and a custom one. Free serves up to 100,000 impressions a month with image ads and charts, described as forever free rather than as a trial. Pro is $10 a month plus usage and Business is $79 a month plus usage, and the usage is the part worth reading: a CPM table on each plan's page starts at $0.0000 for the first 100,000 impressions and falls from $0.07 per thousand into fractions of a cent at volume. A Pro site under the free impression band therefore pays the $10 and nothing more. Business carries a 30 day money back guarantee.

A site owner selling a handful of placements directly who wants to stop pasting HTML into a template. The free tier is the reason to start here rather than anywhere else in this category, because a hundred thousand impressions a month is a real blog. Publishers running video or needing frequency caps are on the paid tiers immediately, and at that point the metered rate matters more than the monthly fee.