One of the most super annoying things about Oracle SQL developer is that it defaults to a not so useful (at least to me) date format along the lines of 15-NOV-11. I prefer to see something helpful like an ISO 8601 formatted date/time.
The solution is to, in Oracle SQL Developer, go to: Tools > Preferences.
Then in the Preferences dialog, select Database and drill down to NLS.
In the NLS parameters you'll be able to set the Date Format to:
YYYY-MM-DD"T"HH24.MI.SSFFTZR"Z"
I have found that on some systems, you may need to use a setting like:
YYYY-MM-DD HH24.MI.SS
References:
http://stackoverflow.com/questions/8134493/how-can-i-set-a-custom-date-time-format-in-oracle-sql-developer
http://orastory.wordpress.com/2007/05/15/dates-timestamps-and-iso-8601/