Product School - The global leader in product management training
Zabbix - Track, record, alert and visualize performance and availability of IT resources
The Product Manifesto - Product Managers face the biggest challenges of our day, which is why our community needs a common set of product principles.
Abusix - Abusix is a network security company that offers email threat protection and network abuse handling solutions to ISPs, Telcos, and Cloud/Hosting Providers to stop the rapidly growing problem of email-borne threats and other kinds of network abuse.
Intercom on Product Management - The ultimate resource for aspiring product managers
FastNetMon - FastNetMon is a very fast DDoS analyzer with sflow/netflow/mirror support.