Here is a collection of the more interesting AIX/Opensource projects currently available in the market. (There are of course others but they are not always actively maintained etc).
Note: Many of these projects also provide a commercial/paid and supported version.
Scripts for AIX
Wireshark network monitoring
Berlin job scheduler
Ganglia monitoring system
AIX Partitions and Systems Performance
General Graphics Interface
OpenSmart system monitoring and reporting tool
IBM MQ explorer tool
System configuration collector
OpenSmart system monitoring tool
AIX Administration scripts
AIX LPP package generator
general libraries and tools