You can also schedule your cron job to run at multiple time intervals. For example, the following cron job will run every hour on Sunday at the minutes 5, 20, and 40:
5,20,40 * * * sun task-to-run
You can also specify a time range. For example, a cron job that will run at 6:30 PM on weekdays (Monday -> Friday) will have the following format:
30 18 * * 1-5 task-to-run
Notice that 0 is Sunday, 1 is Monday, and so on.
To see more cron examples, you can check the fifth section of the crontab man page:
elliot@ubuntu-linux:~$ man 5 crontab