Philosophical Dictionary (by Gather Kemmerling) A reasonably
good resource. However, if you want more detail, consult the
Standford Encyclopedia of Philosophy (below)
An amazing resource! Search an enormous database of philosophy articles. Read articles posted on the web or available (electronically) through your university library (you will have to configure your proxy server for off-campus library access; instructions are on the site and easy to follow).
Philosophy Talk A radio show, from Stanford University. Many audio files of old
Philosophy TV. A web TV show, featuring two philosophers discussing some issue of interest.