Came across a very good weblog on Oracle and Java technologies at http://www.it-eye.nl/weblog/. The blog entries are contributed by the consultants of IT-eye, an IT services company based out of Netherlands.
They seem to be covering quite a number of Oracle technologies ranging from BI, SOA Suite, JDeveloper, Database, and others. Some of the posts on OWB had really good practical insights and this one gives a handy OMB script for creating tables in target module corresponding to every source tables. Probably the script could be extended to create a default mapping to load the data from source to target tables.
One more blog, again from the Netherlands, which I have been following for quite some time now is http://technology.amis.nl/blog/. The folks here share great project experiences on using Oracle technology and Applications offerings. Apart from Oracle technologies, there are often posts on projects executed using Oracle and open source technologies specially those related to Java.