As you can see if you took a moment to Analyze Your Browser, BrowserHawk can tell you a great deal more than whether the user is a crawler or has Flash installed.  Perhaps your site relies on cookies or JavaScript to function properly.  Not all browsers support these features, and most allow paranoid users to turn them off.  BrowserHawk lets you easily see whether these features are available, allowing you to gracefully degrade (or inform the user they need to turn these features on or upgrade to a modern browser).  Perhaps your site includes sensitive information that requires SSL encryption; use BrowserHawk to detect whether the browser supports SSL and if so, what keysize it is using.  Otherwise, your users would receive error messages in their browser if your application tries to engage an SSL session when the user's browser has SSL disabled.

Consider the visual design of your site.  When the Web was young, design guidelines suggested sites be usable at widths no more than 640 pixels wide.  Some years went by, more people bought higher resolution monitors, and these guidelines grew to 800 or even 1000 pixels.  Widescreen laptops today ship with 1680 pixel wide screens, but not everybody who comes to your site will have the same size of screen.  Detect the user's screen size, installed fonts, and text size, and render your site accordingly.

Plugins are cool browser features that don't always "just work," because not all users have them installed.  Flash and Java are the most common browser plugins, but there are many others, including multimedia plugins like QuickTime, RealPlayer, and Media Player.  For many entertainment sites, it's important to know which of these plugins the user has installed so the appropriate media format(s) can be presented.  Similarly, the user's connection speed can be important when determining whether to send a large media clip or a small one, which is where the Broadband and ConnectionSpeed properties come into play.

Now, it's all well and good that you can gather this sort of information about individual users, but what if you really want to know a breakdown of all your users' capabilities?  Sure, you can write your own script to capture this information and store it in a database or something, but BrowserHawk has already done this for you.  Simply configure the component to log statistics (accomplished via a web service on one of your servers), and the rest is done.  You're free to create reports against the data, like these (but note that BrowserHawk does not provide a front end for these reports - it just logs the data).  According to cyScape's users, it looks like only 0.26% of users are on 640x480 displays, while 12% are still using 800x600.  Just about everyone else has at least 1024x768 resolution, with some lucky devils sporting 3840x1024 resolutions.

Going a little deeper into the discussion of web analytics, BrowserHawk's reporting capabilities offer a great deal more depth than most web analysis packages, due to the additional data points it captures from each user.  For instance, you can learn how many of your users have broadband versus dial-up, or have cookies or JavaScript enabled.  This information can be extremely valuable when you're considering how to architect new features for your site.  You can even tie associate session or user ids with the data, so that if a user reports an issue, you can immediately check the database to analyze their browser and system capabilities, which is invaluable for troubleshooting browser-specific problems.