The ad blocking that comes with Camino out of the box is already pretty good. It's configured through a .css file, but the problem is, as set up, it's not customizable. So what do you do if you're satisfied with Camino's ad blocking except for that one obnoxious (or worse) banner ad that it fails to catch? What do you do if your OCD won't let you move on with your life and say, "Hey, it's just a banner ad. Forget about it"?
Well, it turns out there's a way to make Camino's ad blocking customizable with a simple tweek. The .css file that governs ad blocking is actually in the package contents of the .app folder. So first, uncheck "Block web advertising" in Camino preferences and quit Camino. Then control or right-click on Camino.app in your Applications folder and choose "Show Package Contents" from the menu. Then double click on the "Contents" folder, then the "Resources" folder where you will find the file ad_blocking.css. Move this to ~/Library/Application Support/Camino/chrome and rename it to userContent.css. Now you're all set to start customizing ad blocking by opening the file in a text editor and adding new rules.
For example, if you see an image ad you want to block, find the section in the .css file where the lines start with "img" and add the domain from whence the hell spawn arises. Like if you see a banner and find by right clicking on it and choosing "View Image" that it originates from www.ad-douches.com, you add a new line to the "img" section like img[src*="www.ad-douches.com"], (don't leave out the comma at the end). Now all images from said domain will be blocked.
And that's just the beginning of it. There are more tips on customizing .css files here at Mozilla.org.
This same method also works in Firefox. You can download a popular .css file at www.floppymoose.com, but I think the one that comes with Camino is more comprehensive and up-to-date.