Google Adsense isn't any form of spyware, spyware is bad and google is good. Pretty much people would purchase text advertisements from google.com, the person would set their "per click" amount and "cpm" amount, cpm = cost per 1,000 impressions (impression = a view ).
Now, the way the advertisements are setup are:
google_ad_client = "pub-XXXXXXXXXXXXXXXXX";
google_ad_width = 728;
google_ad_height = 90;
google_ad_format = "728x90_as";
google_ad_type = "text_image";
google_color_border = "E5E4D8";
google_color_bg = "E5E4D8";
google_color_link = "000000";
google_color_url = "666666";
google_color_text = "333333";
Now, the code you see at the top "pub-XXXXXXXXXXXXXXXXX" is your google adsense ID ( X's are replaced with numbers ). Anyway, as people visit RouterForums.com and travel through the pages, they advertisements cycle and they change based on which content is relevant on that page. So for example, if there was a thread about router plans on RouterForums.com, google adsense will serve you (the viewer) a text ad based on router plans (bills router plan store). Now, if you click that text advertisement, you'll be directed to the advertisers website (no spyware, virsues, malware involved - COMPLETELY SAFE).
If you're a person who is registered for the RouterForums.com adsense sharing program, and you provide me with your adsense number, also know as "pub-XXXXXXXXXXXXXXXXX". As the advertisements cycle on RouterForums.com, "your", meaning an advertisement served with your pub ID, will be served. Now, if the advertisement is served under your ID, you will recieve all money associated with that. So if the user clicks the ad, you get paid, if 1,000 users view your ads you get paid. At the end of every month you recieve a check in the mail, or a direct deposit to your bank account.
I've been doing it for about a year now, and I've recieved a little over $5,000.00 USD doing it.
I'm pretty much doing all the hard work for you, providing the website to serve the ads. Because without that, you can't get any clicks or make any money.