GlimmerBlocker

As someone who has tried other ad-blockers for Safari, I've found that many of them are implemented poorly, resulting in unstable performance and issues when new Safari versions are released. Specifically, these ad-blockers are often implemented as InputManagers or ApplicationEnhancers. This is where GlimmerBlocker comes in – it is implemented as an http proxy, meaning that the stability of Safari is not compromised in any way. What's more, it is compatible with all other browsers.

One of the biggest benefits of using GlimmerBlocker is that it is easy to upgrade without worrying about breaking Safari, or vice versa. That means you can confidently use beta versions of Safari and nightly builds of WebKit without fear of losing your ability to block ads.

Of course, because GlimmerBlocker does not rely on hacks, there are a few things it can't do. For example, you won't be able to add a block by right-clicking an image, or filter cookies from third-party sites. However, the benefits outweigh the downsides, as you can much more easily add your own modifications to pages using CSS rules, JavaScript or by transforming the HTML before Safari receives it.

If you're comfortable programming in JavaScript, the sky is the limit when it comes to customizations with GlimmerBlocker. In conclusion, I recommend GlimmerBlocker to anyone looking for a stable and effective ad-blocker for Safari, without the downsides of other, hack-based solutions.