Advertisements (Ad) serving for my PC application: How and Who?

Google's Adsense is still a possibility.  As long as you can display it in the app (a proper browser window, javascript must work), you will get what you deserve, because the unique id of yours, is in the javascript (google_ad_client = "xxx")

ok, but how would Google chose and rotate the Ads in that case? I mean, when placed on web site, I believe that Google chooses displayed ads based on the site/page content... how would that function (if would at all), If I would place a WebBrowser control in my app, put in the WebControl a blank page, with the javascript, and hope that Google ads will show up... If the javascript is on a page with no other useful content except the Google's java  script itself, I don't understand how it could funcionate...

No, the google ad code will just display an ad. It doesn't matter what else is on the webpage. Even this code will show you something:

<div class="textwidget"><script type="text/javascript"><!--
google_ad_client = "pub-1813717030888881";
google_ad_width = 120;
google_ad_height = 240;
google_ad_format = "120x240_as";
google_ad_type = "text_image";
google_ad_channel ="";
google_color_border = "336699";
google_color_bg = "FFFFFF";
google_color_link = "0000FF";
google_color_url = "008000";
google_color_text = "000000";
//--></script>
<script type="text/javascript"
  src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script></div>

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And I really mean, JUST that code, no extra code, no text, nothing.
And I just earned money (if you either displayed it on a webform, or you saved it as htm, and opened it in a browser AND clicked on the link).
The extra things you're thinking of (elements to relate to directed ads) are OPTIONAL, it will ALWAYS display a generic ad if no other information is provided.

@Kimputer
Thank you for your post.
I'm very sorry for not replying sooner, but I was away for quite some time...
Anyway, I started testing your, but I can't get it working; I'm probably doing something wrong at the moment, so I'll have to implement it more thoroughly...
However, while searching how to implement this properly, I've stumbled to a Google page: https://support.google.com/adsense/answer/181956?hl=en

" If this is the first time you implement code and your AdSense account has not been fully approved, your ad units will remain blank.
Once our system detects that the code has been placed on a live page, we will automatically review your websites with the ad code. It typically takes 2-3 days for our specialists to complete the review. Once your application is fully approved (you will receive a message about this), the ads will start showing."

Well, If I create my account, doesn't this "Once our system detects that the code has been placed on a live page" and rest mean that this approach would have a problem if running not on a regular site web page, but simply within a WebBrowser control in my program?

You can even have it running on your blog or whatever. As soon as that works, your app will work also. Leave the blog online (even if you don't really use it).

ok, so if I understood you correctly:

a) Create on my site a dedicated "for Google Ads" page, and put on it the Googles' script
b) The page does need to contain some other useful content, (or it does)? i.e. it can be a "blank" page with the script?
c) Google will check the page a hopefully verify it
d) Afterwards, I can simply run the script in WebBrowser control in my program
d2) There is no need to actually load the "dedicated page" in my programs' WebBrowser control, just to execute the script in WebBrowser control, and a Google's add will be shown in the WebBrowser control

yes/no/comment for the steps would be useful

A) Yes
b) preferably at least some content. Maybe 2 or 3 articles
c) yes
d) yes
d2) correct, for now, use my script to test it. After your own ad is working, only change the ID (google_ad_client = "pub-xxx")

I’m not getting any results, but I’m not fluent in Web programing, so I’m probably doing something completely wrong…
1) I tried to implement your code in my WebBrowser control (which shows simple HTML just fine) but I got nothing, i.e. a blank page. I tried to implement your code i two ways:
a) WebBrowser1.Document.body.InnerHTML=YourCode  (following “JUST that code, no extra code, no text, nothing”)
b) assigning your code inside
<html>
<body>
YourCode
</body>
</html>
2) I have also checked https://developers.google.com/custom-search-ads/docs/implementation-guide. When you click on “You may open this example in new tab HERE” you get something I would expect from AdSense. However, if i put the example code on the page in my WebBrowser, I only get a page with 3 lines “Search result 1 Search result 2 Search result 3”. If i put the Google’s example code inside a simple Test.html page and open it with IE, FireFox etc. I get the same result, 3 lines “Search result 1 Search result 2 Search result 3”, and not the useful Ads as if clicked on the Google page, so I’m confused how is this working… Any further help would be greatly appreciated…

any idea?

Thank you for the post.

It seems to work. Sort of.
At first, I created the html file, and tested it with FF, IE8, Chrome, Opera (XP SP3 system)… it would just show the “Hello” text which when clicked would show “Hello World”. I tried the page with WebBrowser control, and it was the same, with addition of reporting script error, so in order to show page I had to use WebBrowser1.ScriptErrorsSuppressed = True (.Net) or WebBrowser1.Silent = True (VB6). I have downloaded and tried WebKit, and it also showed only page with Hello text, without any Ads (in addition, in WebKit browser clicking the Hello text would not bring the Hello World message… I also tried to put explicitly WebKitBrowser1.IsScriptingEnabled = True but i was the same)… At the same time, I can see that Google Ads apparently works just fine in regular web pages opened in FF or Chrome...

Then I tried the page on another computer, XP SP3. And it worked; in FF, IE8, Chrome, and, in my WebBrowser control… it shows a small text Ad with green arrow below. Then I tried on another computer with Win 7, worked with FF, Chrome, Opera, but not IE8 (and hence not in my WebBrowser control). Then I tried on another computer with XP SP3, on which i did not work in any of browsers…

So, although I can consider my question answered, as the sample code in principle works, on the other hand it gives my only hope… as in the current situation it is very unreliable to implement… Do you maybe have idea why this behaves so sporadically, and works only on some systems/browsers? I could blame for instance some scripting settings in IE (for instance in the case of Win 7 system), but it cannot explain why it does not work with FF, Crome, Opera on many systems… And how to amend it so that it works fine?

If you keep using the webbrowser control, you depend on the computer settings on how it's displayed. Since those are OUT OF YOUR CONTROL (it's a system settings, it's a bit strange for a simple app to suddenly change a whole computer's system setting. Even if you manage to figure out how to do it, I would think it's quite rude of you to do so). The Webbrowser control TAKES the computer settings, that's why you have unpredictable outcomes on different PC's.
That's the whole reason I told you about webkit.net!
The ad with the green arrow is the correct ad by the way. At least that's something :)

yes, I agree, WebBrowser is a bit tricky, and changing target system settings just because of WB would deffinetly not be appropriate... While the script occassionaly not working in IE (and WB) is something one can expect, I was more confused why script on many systems does not work for FF, Chrome too... I have not tried webkit on the other systems, but on one I have tested, I also did not display the ad... ghhhh...