SmarterStats 

Improve your web site through extensive statistic reporting. FREE version includes visitor tracking, geographics, and over 135 reports! Works through a web browser so you can get your web site statistics from anywhere! Log analyzer for IIS and more
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siteDirector .NET 

Manage HTTP 404 Errors on all Windows/IIS hosted web sites. Catch 404 page not found errors (HTTP Error 404) and instantly redirect to target resource. Can use tokens for easy handling as well as wildcards.
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httpZip 

Port80's httpZip IIS Web server module reduces bandwidth costs, improves site speed, and better leverages server resources. Powerful HTTP compression reduces page sizes for most common file types and automatically addresses browser incompatibilities.
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httpsentry 

HttpSentry is a free IIS Filter to fight hacker attacks. It prevents common problems such as SQL injection, Directroy traversal and many more. it also supports URL rewrite and Server masking.
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ISAPIZip 

ISAPIZip is an ISAPI plugin which integrates directly into IIS and other web servers to increase the performance while reducing the bandwidth required to serve high quality content.
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IIS Accelerator 

ISAPI filter for high performance HTTP Compression and Content Optimization, Whitespace Removing, Image Optimization, Image Re-compression and much more. Makes Web sites up to 4-times faster. Available for all IIS Web servers.
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