I have just read short about the product and it seemed impressive enough for me to wanna share it.

iBroker can be a good solution but it's aint free, a demo can be downloaded for evaluation.

Source: SecurityFocus Linux Newsletter #91

iBroker SecureWeb Application Firewall

iBroker SecureWeb allows you to protect Web applications from all known and unknown attacks. iBroker SecureWeb wraps around IIS and Apache Web servers and works as plug-in within it, verifying and analyzing incoming and outgoing Web server data for any possible security breaches. It creates an application firewall, which overcomes limitations of Intrusion Detection Systems and Conventional Network Firewalls. iBroker SecureWeb is the most powerful proactive HTTP application firewall... More to read here