Consider Adblock Plus the equivalent of fast-forwarding through the commercials on your DVR. Some ethical arguments could be made against either practice (the advertising pays for the content you are viewing), but in my opinion it is part of the give-and-take among marketplace participants — in this case content creators and content consumers.
This Firefox Add-on blocks nearly all advertisements on most pages and does so without leaving large gaps or noticeably affecting other content as far as I can tell. I have experienced a few webpages where “legitimate” content was blocked by ABP, but it is simple matter to right-click on the stop sign (it looks like when ABP is running) in the status bar of Firefox to turn it off for that particular page or completely .
For an example of what Adblock Plus eliminates, compare the two images below taken from StarTribune.com (you may click on each image to view it on its own). You can see that just on this one page, quite a bit of content is being blocked. Especially for users that are running on slower broadband (or even worse dial-up) Adblock Plus will significantly speed up the browsing experience because a lot of the blocked content consists of bandwidth hogs like images or Flash.
Here are a couple links to check out for more information on Adblock Plus. It installs just like other Firefox Add-ons so if you are familiar with that process it is quite easy. You do need to subscribe to a “filter” that is maintained by others so that ABP will continue to do its job, but that is free and easy as well. The video below walks you through the entire process.