If you’re annoyed at all the ads on webpages, there are different ways to block them in Safari. Ad blocking works in different ways, depending on the software you choose. Some add-ons block by the URL of the ad website, others block by temporarily changing the underlying style code of the web page and others block all Flash-based ads and videos.
But keep in mind that blocking ads might disable some parts of some sites you use – such as banking and online store sites – so after you install any ad blocking software, you may need to adjust it to prevent ad blocking on some of the site you use.
There are reviews of ad blocking add-ons at Pimp My Safari: Adblocking (and the rest of that site might be interesting for other ways to extend Safari with Firefox-like plugins).
I use ClickToFlash, which is a flash blocker. Many web ads are Flash-based, and what ClickToFlash does is stop them from loading. You will see an empty frame on the web page where the flash add or video is, and if you decide you want to see it, click on it, and then the flash will load. This also works for many videos, too. ClickToFlash doesn’t block non-flash ads, so if you want to get rid of all ads on the webpages you read, you need something else.
Safari 5 update: Use ClicktoFlash Safari Extension. “ClickToFlash prevents the Flash plug-in from running. It replaces any Flash element on a webpage with a placeholder; simply click the placeholder to load the Flash content. ClickToFlash also lets you replace Flash videos from select websites (such as YouTube) with H.264 video. Other optional features include advanced whitelisting.” Get it at Apple – Safari – Safari Extensions Gallery
Safari Adblock works well by drawing on a list of ad site URLs from the people who compile it for Ad Block for the Firefox plugin. This gives your copy of Safari a list of URLs to block, and because Safari can’t get to the URL of the ad, it doesn’t load on the webpage.
If you’re using Snow Leopard and want to use Safari Adblock, you need to make a small change to the way that Safari runs. The makers of Safari Adblock are working on a fix, but in the meantime, the simple instructions to make the small change for Snow Leopard are at the Safari AdBlock: block ads in Safari web site, as well as the link to download the utility. Safari Adblock ads another tab in Safari Preferences to enable and disable it, and to also ad your own “rules” to change the way it works.
Another add blocker is GlimmerBlocker, which is a little less capable than Safari Adblock and blocks ads in a different way, but it doesn’t require you to change settings in Safari.