I don't know what traffic, if any, I'd be able to donate, but if it was more than 0 then most likely leaderboard and tower impressions are where it would be - M

I don't know what traffic, if any, I'd be able to donate, but if it was more than 0 then most likely leaderboard and tower impressions are where it would be - MPUs are usually completely sold out. As to non-intrusive, as a general policy it's something I agree on, and we look for in our paid clients (possibly not to the same extent as you, I don't know), but ultimately our sites still fit traditional banner advert sizes. Do the charities not mind about nationality of their audiences? Even if they don't, it often makes a big difference to publishers. For example in my case, US impressions are very different to UK impressions, which are very different to Swedish impressions... etc. edit: I also completely second TylerE's comment, he's absolutely right.