I'm not sure this idea would have the effect you're looking for. The 'watchers' as you referred to them in a comment, probably don't care that you or anybody knows that they're watching. We already know, or at this point assume they are. Beyond that, how would you be gathering the IP addresses used?I assume that what they are running is little more than clever bots which can scrape data and get past most site security. It isn't an actual person going through every page on the internet. They're storing mass amounts of data to do analysis on at a later time.

Basically, the most important things like your Facebook, GMail, mobile and Twitter data are already being gathered. If you saw a little pixel image saying "somebody is capturing your data", would you stop using these services? If not, you're not really having much effect, I don't think.