I have a site that is visited by many, many people on my university campus including people in my own building and my own office who will all have very similar IP addresses to my computer at work. I'm sure some of them have clicked on some of my ads. Should I be worried that google will possibly think there's some click fraud going on, when there absolutely isn't?
i think google uses more than just the IP, like browser version and stuff, but yes, i would be worried. I work for a company without about 10,000 employees in the U.S. - and every one of them is squeezed thru one giant firewall/proxy all with the same internet facing IP.. i was so paranoid that i blocked that IP from my site, even though i never told anyone about it.. Telling your buddies, or everyone on campus about your site might not be a good idea, IMHO ...
I got banned from Digg for the same. About 400o employees in my company uses the same IP and for some digg had blocked our IP altogether. For sites, luckily we filter adsense, so I guess there are no impressions.