HV is Obsessed with WordPress. Are you? Then schedule regular visits to WP’s “Planets”*:
A “planet” is a river-of-news aggregation of blogs on a specific subject.
More Core WP Resources:
WordPress Template Tag Ref (by DBS Interactive ), an quick and easy tool for finding WP function definitions and usage.
PHPXref 0.7: WordPress, lists all WP files and what they do; lists all functions with links to where that function is defined and to all the places in files that call that function.