Those who are accustomed to using Safari AdBlock in Leopard may have been disappointed to lean that the Snow Leopard version is not supported in Safari while running in 64-bit mode. Unfortunately, to use the plugin in 10.6, you must run Safari in 32-bit mode. This is unfortunately the case for many Input Manager plugins that have not yet
 
There exists an alternative to Safari AdBlock which will allow you to run Safari 4 in 64-bits while blocking those pesky ads. GlimmerBlocker is a powerful open source ad blocker that runs as a proxy on your system instead of a Safari plugin. In other words, it works independently from the browser blocking ads as they pass through your computers internet connection. Since it works differently from Safari hacks, there are some minimal disadvantages:

Because GlimmerBlocker doesn’t hack Safari, there is a few things it isn’t able to do: adding a block by right-clicking an image, stopping pop-unders, and filtering cookies from 3rd party sites. But you win a lot in stability, and GlimmerBlocker provides much easier methods for adding your own modifications to pages by adding css rules, pieces of Javascript or by transforming the html before Safari receives it. So I’ll hope you’re happy with the tradeoff.

GlimmerBlocker comes with a simple installer and requires no configuration. Once installed, you will be able to administer it form System Preferences. Apart from blocking ads, it is also has a powerful set of features. Included is a basic set of very useful filters. For example, the Site enhancements filter will put a download link on YouTube video pages. Additionally, keyword expansions allow you to type search queries like “wiki Berlin Wall” or “yt Ballon Boy” directly in the address bar. You may also create and submit your own filters. The possibilities are endless.
GlimmerBlocker can also work on your iPhone when it is connected to Wifi.
You can download the latest version of GlimmerBlocker at glimmerblocker.org.