If your sites uses large amounts of bandwidth consider enabling HTTP compression in your IIS. This feature is available from IIS 5.0 onwards. It compresses web pages and content that is downloaded to a browser running on an end users computer and decompresses it on the fly.
The server first determines if the end user has a compatible browser (IE 4+, Netscape 4+ etc.,). If the browser is compatible, it then pushes down a compressed version of the page to the client. The customers browser then decompresses the file and displays it.
I need to admit that I haven't tried it yet but have read that the feature provided by IIS itself called gzip isn't that stable :( Many say that pipeboost gives us better and reliable functionality.
BTW, do you know that google encodes its content and their pages are tiny?