Database Journal for IBM DB2
http://www.databasejournal.com/features/db2/
Knowledge centre for IBM DB2 database professionals.
DB2 Magazine
http://www.db2mag.com/
A solutions-oriented magazine that provides IT professionals with the strategic and technical information required to work successfully in the IBM Data Management environment.
DB2 Update
http://www.xephon.com/db2update.html
Packed with ideas for improving DB2 - and all the technical details you need to put the ideas into practice.