MySQL Replication question
On the slave, you can configure MySQL to skip certain errors by using the slave-skip-errors configuration item.

In the case above, you'd add the following to your my.cnf;

slave-skip-errors = 1452

But I'd be extremely wary about doing this, as the referential integrity is there for a reason, and without it, your slave could not be satisfactorily promoted to take the place of the master in the case of something going wrong with your master hardware...

http://dev.mysql.com/doc/refman/5.5/en/replication-options-slave.html#option_mysqld_slave-skip-errors