Plexus
Architeuthidae puericomedentis
Firefox is a great browser that is extremely versatile, even more so if you know what features to implement and how to implement them. Feel free to add your own reccomendations.
1. Bookmark Keywords-
Instead of going through a long list of bookmarks for sites that you go to often, Firefox has a feature that allows you to just type in a keyword. IE: instead of typing "www.civfanatics.com", I could just type "cfc". Sound good, right? Well, this is how you'd go about it:
2. Quick Searches-
An awesome feature that I honestly just started using. It is already built into the browser in a limited fashion. IE, if you type google and then a keyword after it, you will be forwarded to Google and Google will search for that. But Google searching is not all you can do. Let's say you'd like to be able to automate Google Image searches:
First, create a new bookmark.
In the "Location:" field, be sure to use a search query for example:
http://images.google.com/images?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%s&btnG=Search
The bolded "%s" will be replaced by whatever you type in what comes after your keyword, ie. "gpix mozilla firefox" would become:
http://images.google.com/images?q=mozilla+firefox&ie=UTF-8&oe=UTF-8&hl=en&btnG=Google+Search
3. Vital extensions:
CopyImage- Adds a 'Copy Image to Clipboard' item to the context menu, below the 'Copy Image Location' item. (Allows copying of images to clipboard).
http://downloads.mozdev.org/database/extensions/copyimage.xpi
Adblock- Adblock is a content-blocking module for the Mozilla and Firefox browsers. It is both more robust and more precise than the built-in image blocker.
http://downloads.mozdev.org/adblock/adblock-0.5-dev.xpi
Things They Left Out- "More Options" appears under the tools menu. There are panels for Languages, MIME-types, security certificates, http, locale, debugging, and networking. You are also able to configure favicons, image resizing, smooth scrolling, and Find as you Type.
http://downloads.mozdev.org/flibble/ttlo2.xpi
All-in-One Gestures- This extension includes mouse gestures with customization, rocker navigation, tab and history scrolling, and autoscrolling similar to that in IE, all in a single package.
http://perso.wanadoo.fr/marc.boullet/ext/allinonegestlatest.xpi
Sort Bookmarks- Sort bookmarks alphabetically.
http://cgi29.plala.or.jp/~mozzarel/addon/firefox/sortbookmarks/sortbookmarks.xpi
Flashblock- Adds an XBL binding to Shockwave Flash object tags that replaces them with a button you must click in order to play the animation. Quite nice for restoring sanity to your browsing session.
http://downloads.mozdev.org/flashblock/flashblock.xpi
Bookmark Backup- An extremely basic extension that creates a backup of the bookmarks file each time Firefox is closed. The backups can be found in the Firefox profile directory. They will be named bookmarks.html.<day> e.g. bookmarks.html.sun, bookmarks.html.mon, bookmarks.html.tue, etc. If Firefox's bookmarks become corrupted or lost simply find the backup for the previous day and rename it to bookmarks.html. (if necessary delete the corrupted version first).
http://www.pikey.me.uk/mozilla/extensions/bookmarkbackup.xpi
IE View- Adds "View page in Internet Explorer" links to the content and link context menu. Handy for previewing pages in IE, loading up IE-only pages when you run across them in Mozilla, etc.
http://downloads.mozdev.org/ieview/ieview.xpi
1. Bookmark Keywords-
Instead of going through a long list of bookmarks for sites that you go to often, Firefox has a feature that allows you to just type in a keyword. IE: instead of typing "www.civfanatics.com", I could just type "cfc". Sound good, right? Well, this is how you'd go about it:

2. Quick Searches-
An awesome feature that I honestly just started using. It is already built into the browser in a limited fashion. IE, if you type google and then a keyword after it, you will be forwarded to Google and Google will search for that. But Google searching is not all you can do. Let's say you'd like to be able to automate Google Image searches:
First, create a new bookmark.

In the "Location:" field, be sure to use a search query for example:
http://images.google.com/images?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%s&btnG=Search
The bolded "%s" will be replaced by whatever you type in what comes after your keyword, ie. "gpix mozilla firefox" would become:
http://images.google.com/images?q=mozilla+firefox&ie=UTF-8&oe=UTF-8&hl=en&btnG=Google+Search
3. Vital extensions:
CopyImage- Adds a 'Copy Image to Clipboard' item to the context menu, below the 'Copy Image Location' item. (Allows copying of images to clipboard).
http://downloads.mozdev.org/database/extensions/copyimage.xpi
Adblock- Adblock is a content-blocking module for the Mozilla and Firefox browsers. It is both more robust and more precise than the built-in image blocker.
http://downloads.mozdev.org/adblock/adblock-0.5-dev.xpi
Things They Left Out- "More Options" appears under the tools menu. There are panels for Languages, MIME-types, security certificates, http, locale, debugging, and networking. You are also able to configure favicons, image resizing, smooth scrolling, and Find as you Type.
http://downloads.mozdev.org/flibble/ttlo2.xpi
All-in-One Gestures- This extension includes mouse gestures with customization, rocker navigation, tab and history scrolling, and autoscrolling similar to that in IE, all in a single package.
http://perso.wanadoo.fr/marc.boullet/ext/allinonegestlatest.xpi
Sort Bookmarks- Sort bookmarks alphabetically.
http://cgi29.plala.or.jp/~mozzarel/addon/firefox/sortbookmarks/sortbookmarks.xpi
Flashblock- Adds an XBL binding to Shockwave Flash object tags that replaces them with a button you must click in order to play the animation. Quite nice for restoring sanity to your browsing session.
http://downloads.mozdev.org/flashblock/flashblock.xpi
Bookmark Backup- An extremely basic extension that creates a backup of the bookmarks file each time Firefox is closed. The backups can be found in the Firefox profile directory. They will be named bookmarks.html.<day> e.g. bookmarks.html.sun, bookmarks.html.mon, bookmarks.html.tue, etc. If Firefox's bookmarks become corrupted or lost simply find the backup for the previous day and rename it to bookmarks.html. (if necessary delete the corrupted version first).
http://www.pikey.me.uk/mozilla/extensions/bookmarkbackup.xpi
IE View- Adds "View page in Internet Explorer" links to the content and link context menu. Handy for previewing pages in IE, loading up IE-only pages when you run across them in Mozilla, etc.
http://downloads.mozdev.org/ieview/ieview.xpi