Google Open Source - All of Googles open source projects under a single umbrella
AWS CloudTrail - AWS CloudTrail is a web service that records AWS API calls for your account and delivers log files to you.
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Logmatic - Logmatic is a log centralization, analytics & visualization platform to improve software & business performance.
Open Source @IFTTT - A collection of IFTTT OSS projects.
log4net - log4net is a tool to help the programmer output log statements to a variety of output targets.