Adblock Plus

I'm using firefox for little over a year with adblock, and am wondering about Admuncher, is it really all that great, being as i dont know if its free or not, and it is probably not as configurable as Adblock+, but it works for all browsers...

Adblock and Admuncher are entirely different things. Admuncher alters the HTML code of the web pages you are receiving. While you can remove ads this way, you are also likely to break some web pages. Web pages always rely that the users get them unchanged. And I've seen quite a few people complaining because their ad blocker changed the code of an XHTML page assuming it is normal HTML, Firefox would refuse to display the page afterwards. I don't know how much this applies to Admuncher but the danger is always there.

Adblock (all versions) works on a very different level. It doesn't touch the HTML code (object tabs are an exception and these are meant to be as little intrusive as only possible). From the webpage's point of view the ads simply failed to load - something that can always happen, not a drama.

I see.. so how do some websites absolutely know you've blocked there ads.. is there way to trick them?

Its offtopic since this is the AdBlock Plus forum.
But I suggest to take a look at this:

http://bfilter.sourceforge.net/

It is a "local proxy" that filters the ads with some kind of "euristic" engine.
Plus it is opensource software, on Sourceforge, not a commercial product.

The difference between using an extension and a "local proxy" to filter ads is mainly in the resources required. In theory the extension should be much lighter because it works on top of the browser instead of being an indipendent software. The drawback is you can use AdBlock only with Firefox, while the "local proxy" works for ANY browser (es. for IE).