ThreatSentry 

ThreatSentry Windows Web server Host Intrusion Prevention software defends IIS against new and progressive attack techniques, protects network weak points, overcomes lapses in patch management, and reinforces regulatory compliance.
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ETagFix 

ETagFix is an ISAPI plugin which integrates directly into IIS and other web servers to alter the etag that IIS produces so that web crawlers will not check your web site so often.
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CacheRight 

CacheRight for IIS allows developers to set reliable cache control policies for images and other site content without MMC access. It will speed up pages, reduce bandwidth expenses, and ease server strain from unnecessary validation requests.
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Mail Storage Guard 

Mail Storage Guard is an extension for Microsoft Exchange Server 2000/2003 and IIS SMTP servers, designed to protect your server from spam, prevents mail relaying, mail-bomb and NDR attacks. Works at SMTP and at storage levels.
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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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Bandwidth Buddy for ASP.NET 

Bandwidth savings - ASPX pages compress by ~65%. Fast page loading - The major delay is transferring HTML from the server to the browser. So a page may load 2-3 times faster. Configured per site - Access to IIS manager not needed. Web services
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