Application Development: Python and Django, PHP, Ruby, C#
Platforms: Unix (Linux, Solaris, AIX), OSX
Databases: MySQL
System Software: Apache, Lighttpd, Tornado, Varnish, nginx, PHP, Python, Memcached, Ejabberd, Qmail, Postfix, Courier-IMAPd, Endeca
Cloud Infrastructure: Rackspace Cloud, Slicehost, AWS (S3, ec2, EBS, SimpleDB), Zerigo DNS
Security: PGP, Nessus, NMap, ACiD, Snort, Portsentry, IPF, Linux Firewalling, General Linux security
Markup Languages: HTML, XHTML, CSS, XML, XSLT
References available on request.