I have no experience with "inviting advertisers." Sorry, never heard of that.

What I do know is that a large percentage of ads come from brokers. These are companies that send bots out to crawl our pages, glean that data and bundle it into products they sell to their clients. These advertisers are usually not the individual guy, but larger companies that don't have the time to surf around and check out websites to place ads on so they pay a 3rd party to do it, the broker.

So make sure you don't block any of the 200 or 300 marketing bots.

Related information: Search Engine Spider & User Agent ID Forum [webmasterworld.com]

Seeking adwords advertisers seems a bit odd ... after all ,they are already in a "shove it where it fits with who the heck is out there" kind of biz.

Having a notice you are willing to take on DIRECT advertising (and host those ads yourself, too) might be a different proposition worth pursuing. In that case, make sure you have the current traffic stats and other metrics to sell that to any that might inquire.

MEANWHILE, if you are really interested, then have all the above in hand and GO COLD CALL businesses and industries that have a fit for your site/content and sell it. Works a treat (but is hard work). Pays a lot better than anything an automated third party can do for you.

Runfun - Since you placed this question in the Google AdSense Forum, I assumed you were asking about attracting AdSense advertisers.

I sell ads on my sites directly as well. It's become difficult with all the competition, but do still get several niche specific advertisers a month with maybe 25% returning for additional campaigns. I consider that pretty good.

Direct advertisers earn a lot more than all other kind of advertising options. But it's difficult to fill it every month and I don't have the time to have talks with potential advertisers. The point was I noticed a textlink once with an invitation to AdWords users to advertise on a website. At the other hand, with Google taking a lot of the profit it's not the best solution.

In another thread here I shared my way of serving of ads and it's like this:

1) rotation of affiliate ads with a frequency cap
2) header bidding competing with Adsense
3) unfilled impressions are filled with Adsense

There was such feature 13 years ago (how time flies!) [googlepress.blogspot.com...]

Google retired the feature at the end of 2007.