I am now using version 3, though I held off switching my home computers till the first revision. Despite beta testing, bugs seem to be found quickly in x.0 versions of software and it seems prudent to wait and download x.0.1 or x.1 versions.
There are 2 features I find very useful with Firefox. The first is the new address bar in version 3. For those who do not use version 3 or use some other browser this is an extremely helpful feature. Firefox searches thru your history and any word/ phrase that you type that is found anywhere in the URL address or in the title of the webpage is offered as a suggestion. If you were reading an article (or 2) on Saturn and the title of the page had the word "Saturn" in it, then type in "Saturn" in the address bar and all the pages will be offered in the suggestion box. The suggestions are sorted according to frequency of page loads and how recently the page has been visited. For frequent sites I do not frequently use clickable links or bookmarks, I type the first few letters and select the site.
The second is an add-on I use very frequently called DictionarySearch. It is so useful and small enough that it possibly could be included within the browser. The intention of the addon is to allow people to look up words in dictionaries. Just highlight a word, right click and select search for the word in an online dictionary. Now I use it for that, but it allows up to 4 dictionaries. It allows you to search any site that allows searching from the address line. So my searches are:
These searches or web address lookups occur in the background while I continue reading.
The dictionary is obvious. Wikipedia I use for basic information on topics or people I am not familiar with. The Bible search is also very useful. When verses are referenced but not quoted I highlight the reference and the page loads with the relevant verse(s). Also when reading or writing (blogging or comboxes) I can highlight a phrase (ie. not a verse reference) and search for that phrase within the Bible.
Text: Find "$"Try it.
Text: Search dictionary for "$"
Text: Search ESV for "$"