We have seen lots of websites and "gurus" showing how they earn their big bucks from ads program, I ask: Is their a real-life example who earn at least $100 a day on an individual website (not all your websites combined).

Do a search from Yahoo! answer:

One of the best success story with Adsense is Markus Finch, who operates the immensely popular online dating website PlentyofFish.com http://www.webmasterworld.com/forum89/12...
PlentyofFish.com's business model is different from the subscription based model used by the big online dating websites. Instead of subscriptions, Markus relies on advertising, specifically Google Adsense to derive income from his website. In a post at Webmasterworld.com, Markus reveals that he has earned $1 million from Adsense alone in 3 months, and the lessons he shares are:
1. Understand your traffic and how it could affect your keywords.
2. Create sites that will bring in repeat traffic.
3. Have your users create content and lots of it.
4. Do not enter markets with a lot of competition monitized via adsense.
5. Keep your site simple.
6. Learn from various forums and if people are not talking about your market, there is a good chance you will make money.

It is not easy to predict how much you will earn from Adsense. The only way you can learn about how your site will perform with Adsense is through trying it. The amount you can earn will depend on the
1. Responsiveness of audience to the ads = Users looking to book a travel to Spain comes to your site about tourist destinations in Spain is a site that will do well with Adsense as users are more likely to click on an ad about hotels in Spain. However, if you are a gaming website where the main purpose of the user is to play games on your site, then Adsense will not perform as well.
2. Ad format = some types of ads do better than others depending on your content and layout. In our case, large rectangles in the middle of the content is the best, while leaderboards do not generate as much as income. Skys are the worst for us. Experiment and measure the results via channels and see which formats work best for you.
3. Ad placement - check Google's heat map as they have tested where the best placements are https://www.google.com/support/adsense/b...
4. Ad colors - sometimes ads blended into the content works wonders, but sometimes ads that contrast your site colors work best
5. Number of ad units on a page = we are allowed maximum of 3 ads + 1 ad links + 1 search box on a page. Maximize the allowed number based on the resulting look of your page (you don't want an overkill of ads). Users going to your page and reading your content may ignore the banner or rectangle at the top of the page, but may click on the ad at the bottom of the article
6. Smartpricing - the big unknown in Adsense. No one knows how this actually works.

Experiment with the factors above (except smartpricing, which you can't control), and see which combination works best. Remember though that not all sites do well with Adsense - even if you get gazillions of traffic but your visitors are not interested in looking for ways to spend their money, they won't be interested in your ads and won't click.