Normally when you backup a database the log files are automatically truncated, however recently we had a development database that had racked up a 9GB log file! Despite nightly backup's the log file wouldn't clear.
In order to shrink it down to a manageable size I ran the following commands from Query Analyzer:
BACKUP LOG DBName WITH TRUNCATE_ONLY
GO
DBCC SHRINKFILE(LogFileName,SizeInMB)
GO
Now all I have to do is figure out why it get so large in the first place.