InfoBarrel is one of the content sites that you can provide content in exchange for 75% of the adsense impressions. You can't use direct affiliate links, no links in the first paragraph, and no more than 2 self-serving links in the content. DoFollow (last time I checked). Here's a copy + paste of their email announcing a vacation/travel article contest on the site. If you join you can also sign up other writers under you. No affiliate links are contained in the below. Enjoy.
Cheers,
James

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So summer is fast approaching and many people will be looking up places to get away to, so we are going to focus the contest to cover that area. This month's topic is going to be vacationing and travel destinations. You can write on anything from great road trip routes to your favorite hidden away camp site (if you want to give up that info, that is). We will also keep up the holiday themed articles, like Independance Day, Canada Day, Father's Day, and anything else you can think of.

As always, any article written on Vacationing, Travel Destinations or upcoming holidays will get you a 1% increase on your ad share for the month of June 2010, up to a maximum of 5% increase. You will also get a 5% increase in your ad share if you get over 20 points and a 10% increase if you get over 30 points.

So to sum up, You will get a 1% increase on your ad share for the month June 2010 for every Vacationing, Travel Destination or Holiday themed article written this month, up to a maximum increase of 5%. You will also get a 5% increase for getting over 20 points and another 5% for getting over 30 points, giving you a maximum ad share of 90%! Oh, and the writer with the highest point totals will get a $100 Amazon gift card, the second highest gets a $50 Amazon gift card and the third highest gets a $25 Amazon gift card.

Each article will still be worth 1 point for 500+ words, 2 points for 800+ words and 5 points for 1000+ words.

After you have completed your articles we ask that you send us an email (via the Contact Us page) with the titles of your themed articles so that we can verify them and give you your ad share in June. Please try to send only one email as the more emails we receive the longer it is going to take us to read them all.

Prizes:
Member with the most points - $100 Amazon.com gift card

Member with the second most points - $50 Amazon.com gift card

Member with the third most points - $25 Amazon.com gift card

Achieve more than 30 points - 85% Adsense Share

Achieve more than 20 points - 80% Adsense Share

For every themed article written receive an extra 1% Adsense Share, up to a maximum of 5%.

How do Points Work?
1 Point - 500+ Words
2 Points - 800+ Words
5 Points - 1000+ words

You MUST email us your themed article titles by the end of June 1, 2010 for them to count.

Any questions, please email us via the Contact Us (http://www.infobarrel.com/Contact_us) page.

Note: All articles involved in the contest must remain on the site in order to qualify for the prizes. If articles are removed they will not be counted towards your point totals.
Check out the contest details and standings here: <http://www.infobarrel.com/contests.php?id=16> http://www.infobarrel.com/contests.php?id=16

Thanks and happy writing!
The InfoBarrel Team