Sweet sites and friggin’ awesome Free and Open Source Software

NameCatagoryWhy I love it..
InfraRecorderDiscISO creation/writing utility software
netboxNetworkingNew kid on the block from DigitalOcean for a true IPAM solutions.
iPerfNetworkingThe DeFacto tool for measuring true link bandwidth and latency between two end points.
phpIPAMNetworkingIP Address Management at its finest.
GraylogSyslogA fantastic log aggregator to parse through all your lovely log messages from any source.
MTRNetworkingThis tool will provide real-time stats of every hop in an IP path between SRC and DST.
MediaWikiCMSA wiki package written in PHP. Its become my go-to documentation management system and is without equal.
Excellent screenshot software that automatically prompts for save after selecting screen area to capture.

OSI Model Reference Chart