People who develop websites have probably already heard of Firebug and the Web Developer Toolbar. They are two very popular addon tools for Firefox that let you analyze web content as delivered to the browser.  The beauty of tools like this is that you don't have to leave a page you're viewing in order to debug it or test code.  There's no need to transfer files to/from a server and reload the page.  If you like these two tools, then consider several others profiled in an article from Smashing Magazine called: 15 Helpful In-Browser Web Development Tools.
Tools they profile include the following:

• YSlow: a tool from Yahoo! that integrates with Firebug to test website speed and suggest ways to improve it
• Internet Explorer Web Developer Toolbar: A Microsoft program similar to the same addon for Firefox
• FireShot: A tool for capturing and analyzing parts of images delivered to the browser, falling somewhere between Screengrab! and Snagit in terms of features
  
• Fangs: A free screenreader tool to test oral rendering and navigation of websites (similar to the commercial product "Jaws")

There's some overlap in features between the programs profiled.  For instance, the toolbar from chrispederick.com includes color analysis options similar to those in Colorzilla (for color palette analysis). Nonetheless, it's nice to see a list of these tools that include addons for Internet Explorer, Opera and WebKit (aka Safari / Chrome).  Firefox isn't the only browser that supports in-browser editing, afterall!
Hat tip: Boagworld podcast (which mentioned the Smashing Magazine article).

Internet Explorer users have a new tool to make use of Microformats even easier. The tool is called Oomph: A Microformats Toolkit, which was released as test software. Once installed, this runs as an addon in Internet Explorer to recognize pages that contain contact information or event details marked up with Microformat code. Then a nice little microformat icon shows up and you can interact with the data to save contacts to your address book or put events on your calendar.

Read more about the new tool in a blog post Microsoft and Microformats from John Allsopp, who literally wrote the book on microformats.

Here are some pictures:

Some screenshots of demonstrating microformat interaction in Internet Explorer.

You can already take advantage of microformats, even without creating them yourself. For instance, you might find events in Yahoo! Upcoming and add them directly to your calendar. Or you can search Google Maps or Yahoo! Maps and add them to your phone. There's a strange limitation to Yahoo! and Google address mark-up however. They don't include phone numbers or zip codes. I think this is by design and not a mistake. It's still pretty useful though.

Firefox users should still rely on the Operator Addon. Operator recognizes more microformats than Oomph, and there are more debugging tools for developers.

If you've ever wanted to do any usability testing of your website, there's a new program just released that may be a great option. It's called Silverback, and it sounds like a promising program. The one downside is that it is only available for the Mac platform, so an unappologetic Windows user like me has to wait for a while before using this.

If you're in the market for usability software, consider Silverback. You can try it free for 30 days, and a single copy is around $50, which is much better than the roughly $1500 street price for Morae from TechSmith. That said, we used Morae for usability testing when we redesigned our website at Georgetown, and it was well worth the money we spent on it.

At the risk of providing lots of free advertising for a company's product I haven't tested, here's a video explaining Silverback:

Silverback screencast from Jeremy Keith on Vimeo.

In testing Microsoft Internet Explorer 8, I came across a funny bug to the system: Microsoft doesn't recognize it as a supported browser for doing automatic updates! One feature of the browser is that you can set it to emulate IE7. With this in place, it does work to get the updates, but it seems pretty darned funny that the newer (and more standards-compliant) browser isn't seen as being 'approved'.

Here are some pictures of the IE8 error screen. Also, there's a picture of a page from Yahoo!'s Upcoming site showing that their maps don't render correctly. IE8 is not exacly ready for prime time, but hopefully it will be soon.

Of course, we'll see how it compares to Firefox 3 for download counts when it's officially released.

If you work at an organization that runs Microsoft Exchange, you can probably share contacts and schedules fairly easily. The only problem is that these features mean nothing if you can't find email and sort out all of the messages that sit in your account. There are now two current programs in beta that attempt to make Outlook email much better. The latest one is called ClearContext Personal. The personal edition is free right now, with a professional version to be sold at a later date. The main features are intended to let you organize email better, browse attachments and leverage some existing (but often underused) features of Outlook that color-code your contacts for priority, and let you apply automatic sorting rules to conversations and contacts.

To work most effectively, you probably want to rely entirely on the ClearContext way of repackaging Outlook, which may require slight changes to your email reading habits. Whereas the program Xobni reindexes your email and presents your options mostly in their separate windows, ClearContext is more integrated with specific features of the Outlook application. Possibly the two can coexist on the same machine, but probably they are two alternatives to consider.

Here are three screen shots of ClearContext to see how it appears:
A view of the attachment explorer in context of the Outlook 2007 email client

and this same image closer up

ClearContext options for reorganizing your email sorting and performing other operations to make messages easier to manage.

TechCrunch has a good overview of some core features of ClearContext Personal.