You are probably already using the Mozilla web browser. If not, you should have a very good reason, or you should go and download it now. Mozilla is (in my opinion) the best web browser out there. There may be some better browsers if you're running Linux, but if you're in Microsoft's world, Mozilla wins, hands-down. It's fast, standards-compliant, and has so, so many advantages over Internet Explorer. (What about Netscape? Well, Netscape uses Mozilla code as its source). In any case, go over to Mozilla.org and get the latest stable release (or the alpha, and help them find new bugs!)
OK, enough preaching to the choir. You use Mozilla, you've been using it since the pre-1.0 versions, maybe you even have a Bugzilla account and submitted bugs 'back in the day'. But if you've seen an ad - any ad - recently, you're not getting the most out of your Mozilla browser.
First off, there's image blocking. This is on the right-click menu when your mouse is over an image. You can select "Block all images from this server" -- which, if it happens to be an ad server, means you'll block all the ads from that server forever. Spend 10 minutes going to your favorite websites and blocking ads, and you'll be free!
There is some danger -- some ads (Slashdot, and a few at Yahoo, for example) are served by the same computers that give you the page navigation graphics, so blocking the ads blocks all the images on the page. Luckily, you can right-click again on where an image should be and find the "Unblock all images from this server" command.
I despise pop-ups, pop-unders, and most things that have 'pop' in their name, excepting popcorn. Luckily, Mozilla cares about empowering the user, and gives you the power to control what permissions javascripts have on your personal computer. My favorite is to deny javascripts the right to open unrequested windows. What this means is that unless you actively click on something that opens a window, the javascripts can't do anything -- which means, in non-geek-speak, that you'll never see another pop-up/under ad again, or be trapped in a series of web pages that open five more every time you try to close one. Luckily, this is such a popular feature among users that it moved out from being something you had to edit a special prefs.js file to get to a feature in the javascript control panel, and, in the newest version, an option under Privacy and Security. If you have version 1.3 or earlier, it is under edit-preferences-advanced-Scripts and Plugins, and is the first option, "Open unrequested windows" should be disabled. There's lots more in there, for privacy freaks -- prevent javascripts from reading cookies, hiding the status bar, moving or resizing windows.... In the newest versions of Mozilla, these features are all in the same place, but the "open unrequested windows" is now ###find new location for js popup blocker! ###
Imagine a world where you could say, type some words in to your web browser, and it would automatically go to Google for you and give you all the results. Further, imagine that you could click on these results and each page would be connected in one browser window, each in its own tab, instead of scattered across countless different browsers all across your desktop. And even further, what if you found a group of pages -- say five -- that all contained some information about a problem you're trying to solve, and want to save them for later? Imagine that you could bookmark them as a group!
Of course this is possible in Mozilla. Tabbed browsing seems a bit odd at first, but use it for a day, and you'll be hooked. You can right-click a link and choose the option "Open in a new tab". I prefer the setting where it opens the link in a tab and keeps the window you're working on in focus, so you can open pages in the background, but not loose track of them. This option is (for now) buried under Edit-Preferences-Navigator-Tabbed Browsing. As for the bookmarking, it's under Bookmarks-Bookmark this group of tabs. I have two set up -- every morning I check my mail, Livejournal, and a few other sites, and then a group of news sites (Slashdot, Memepool, NYT), each of these groups is saved as one bookmark, so opening it opens the entire group in one tabbed browser. This does take a bit of getting used to -- no more alt-tabbing to the other browser, you use alt-Pg Up and -Pg Dn to navigate between tabs.
OK, this was done a long time ago, but Mozilla made it such that you can choose which search engine you want to use, instead of forcing you to use one. It comes pre-configured with Netscape, DMOZ, and Google available, and you can add your own. The settings for this are at Edit-Preferences-Navigator-Internet Search. DMOZ, by the way, is a wonderful catalog site, like Yahoo used to be, with everything organized by volunteers into specific categories -- both Yahoo and Google use DMOZ on the backend to help organize and sort links.
You can of course store passwords for websites you visit often in Mozilla. But if you feel uncomfortable about doing this, you can set a master password, end even encrypt your stored passwords, such that you have to enter a password to enable the stored passwords -- very useful in an office environment or a cyber centre. These options are under Edit-Preferences-Privacy&Security-Passwords and -Master Passwords. You can set it to require the master password the first time it is needed during a session, or even after a time-out period you choose.
I finally gave up on cookies. Every now and again I'll go on a cookie-hunt, but between Ad-Aware and hacking my HOSTS file (all of the sudden, ad.doubleclick.com resolves to localhost! how odd.), I don't acquire that many bad cookies. Nevertheless, Mozilla gives you multiple cookie-control options, from forcing time-outs for cookies without expiration dates to blocking cookies outright. More useful is the management feature, available under the Tools menu, which lets you remove individual cookies with or without the option of letting the server re-send the cookie, as well as blocking/unblocking cookies from the current site.
One thing that's supremely annoying is getting to the end of a long long form, pressing next, and finding that your Internet connection's gone down, or the server is misconfigured, or whatever, but loosing all your time filling in the form. Mozilla now enables you to save specific forms, and also lets you fill in basic personal information, and will try to automatically fill out forms with it if you like. These tools are under Tools-Form Manager.
Finally, Web developers have access to hoards of useful tools in Mozilla. The one I use most often is the JavaScript Console, which gives line numbers, coherent errors, and a code snippet to point out my bungling errors in javascripts. You can also apply stylesheets to any site you're viewing (also useful for bad websites), and viewing the source is a CTRL-U away! In frames, you have context-sensitive right-clicks that let you view the source for the frame your mouse is in, as well.
Are you convinced? Are you using Mozilla now? It's the best thing for HTML since Mosaic (Mozilla's namesake). If not, or if you have ideas I didn't include, feel free to email me...