I block everything or not (if I site has that much stuff, I probably don't want anything loading from it since it's not just third parties that could be problematic as the site probably performs like crap with local stuff too). If I don't trust a certain third party, I just add it to my hosts file as it's probably common on a lot of sites.
Finding them involves using Opera Dragonfly, Firebug in Firefox or Live HTTP headers a Firefox Addon (or whatever similar in your browser of choice). Granted that's not easy for everyone to do, but I think most on HN could do that if they wished. Though that's what works for me and I'm just sharing in response to your request :)
Too late to edit my previous post, but if you would like to see my host file list, I can paste it somewhere. Some of it is from other lists and quite a bit is things I add.
Finding them involves using Opera Dragonfly, Firebug in Firefox or Live HTTP headers a Firefox Addon (or whatever similar in your browser of choice). Granted that's not easy for everyone to do, but I think most on HN could do that if they wished. Though that's what works for me and I'm just sharing in response to your request :)