Best Ads to Display?

Hey everyone. For those of you who don't know, I am starting a free host (IsMyWebsite). I'm trying to brainstorm some creative ways to get ads on people's sites that blend in. To get ads that webmasters would be proud to display and visitors would willingly click. Here's some ideas I have so far:

1) Random Site
Basically, it's a little box on the page that displays a link to a random website - possibly targeted to have something in common with the source page. Could be a text link or 88*31 button. There might also be a 'Randomize' button to pick another site.

2) 88*31 Cool Links
Somewhere between 4 to 6 randomly selected 88*31 image links in a box titled 'Cool Websites' or 'Cool Links' or 'More Great Sites'.

3) Text Cool Links
Like above only with text links. Not sure whether it would include descriptions.

4) Grafitti Wall
Basically, advertisers would purchase 16*16 pieces of an ad page. When a site was visited, an advertisement wall related to the site would be displayed.

Can you tell me:

1) As a site owner, which would you prefer?

2) As an advertiser, which would you prefer?

3) Any comments about these possibilities.

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