If you are a full time affiliate marketer there is a very good chance that you not likely don't use Internet Explorer. There are a number of reasons that change most people, but that is the most, the lack of plugin functionality & 3rd party integration.
Firefox really embraced these types of applications and allows you, them seamlessly into your regular workflow to help you, tasks or use functions, that the original developer do not hard code.
I use a number of Firefox extensions that really make a big difference to my workflow & productivity but the purpose of this article to be the final list of Firefox plugins for affiliate marketers:
If you have more computer & workstations painful to keep always your bookmarks synchronized, especially if you have hundreds of sites. Foxmarks will save all your Firefox bookmarks externally and then keep them updated & sync no matter where you go (if you have installed the extension on the computer). This means that the bookmark on all my computer always match, a massive time saver for me.
Greasemonkey is an extension for Firefox with which you write or download scripts that change, such as Web pages behavior or search. There are literally thousands of user written scripts that do all sorts of things to remove the annoying parts of MySpace from download YouTube videos (I thought it was but all annoying?) 
) or point the link data in Google Webmaster Tools.
You can this extension to the Google search results from different locations around the world, to the regions, see cities & postal codes. Especially useful if you are running PPC campaigns outside your geo-location, and also if you want to see, which are about your international competitors.
I spoke about how much I like for this plugin but when fast analysis takes you on a specific keyword or niche or an any other search then this plugin is gold. It can for you quickly see the incoming links to a domain or an idea idea get a page if the page has page rank & many other features.
Get a quick snapshot of the page rank & Alexa rank if a certain page. Well for the analysis quick the popularity of a particular site/page.
This is a very useful extension that allows you to manipulate, apply many of the design features within a page. You can disable meta redirects, Java, CSS and referrer; Clear cookies and disable cookies; Also edit resize pages & elements & shapes. Very very useful.
Respond move between user agents within Firefox to see, such as Web pages. Useful for getting into sections, which allow only Googlebot (naughty naughty) & a few other things.
The HTTP headers of a Web site map in real time. This can be used redirects for the debugging to see what cookies are set and to check.
I use RoboForm fill forms & give also signup information for new sites. Saves a considerable amount of time, if you properly set it up.
All webmasters need to take screenshots once in a while. I love this extension especially because you can take an entire page as a screenshot.
GSpace is a great extension that your 2 GB disk space into Gmail in your own file storage space. Really useful for storing backups & file transfer between sites, fast & secure.
Manage multiple Gmail accounts from an extension. This extension is especially useful if you have migrated to Gmail, described in one of my previous posts.
If you want all your passwords with KeePass manage this tool allows you to then all your Firefox passwords in XML or CSV format export, which you can then use to import into KeePass. Nifty. Now all we need is an extension for Firefox that integrates with KeePass (hint hint).
How can this extension select in Linux any text & have copied automatically to the Clipboard.
Falsify your referrers easily. This is pretty good, if you catch someone out who is cloaking or test/hack others want to referrer things related.
Using other plugins, you feel increasing your productivity or help you with affiliate marketing then let me know about them in the comments & help grow this list.