I wish I could remember the original source, but I was reminded again today that Microsoft is accepting malware samples via two distinct email aliases.  (Since writing this Silverstr's blog at http://silverstr.ufies.org/blog/ was pointed out to me)

If you encounter some nastiness that you'd like to see Microsoft include in their monthly MRT updates send email to the following Microsoft email addresses depending on sample type, *Correction* and please use the AV industry standard password for malware samples of 'infected' to protect a zip or rar file containing your submitted sample.

William Salusky
Handler on duty ;)