This group at the university of Linz offers lots of public domain packages for the Oberon System V4, as well as they continue to maintain this Oberon System variant.
Oberon (Oberon-2 focus) information, compiler and system implementation table, AlphaOberon-2 compiler user guide (64-bit, for HP OpenVMS Alpha), comparisons, downloads, links.
Very nice GUI library for Optimizing Oberon Compiler (OOC) to make platform independent graphic programs using set of standard and advanced controls, advanced layout engine. Runs on all Unix systems with X Window. [Open Source, LGPL]