Below is a list of resources that can be used to analyze web based threats, viruses and malware. I will update this list continually.
Web Analysis Services
Virus Total - http://www.virustotal.com/
Wepawet - http://wepawet.iseclab.org/
Virus.org - http://scanner.virus.org/
JSUnpack - http://jsunpack.jeek.org/dec/api
Web Sniffer - http://web-sniffer.net/
Applications and Plugins
Malzilla - http://sourceforge.net/projects/malzilla/
Process Monitor - http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx
McAfee File Insight - http://www.trustedsource.org/blog/294/New-Version-of-McAfee-FileInsight
TrendMicro Web Protection Add-On - http://free.antivirus.com/web-protection-add-on/
Sophos Anti-Rootkit - http://www.sophos.com/products/free-tools/sophos-anti-rootkit.html
Avast - http://www.avast.com
Firebug - http://getfirebug.com/
NoScript - http://noscript.net/
McAfee Site Advisor - http://www.siteadvisor.com/
Web of Trust - http://www.mywot.com/
KeyScrambler - http://www.qfxsoftware.com/Download.htm
URL Databases
Malware URL - http://www.malwareurl.com/
Malware Domain List - http://www.malwaredomainlist.com/
HP Hosts - http://hosts-file.net/
Phishtank- http://www.phishtank.com