One of the great things about Amazon Redshift is that it's based on PostgreSQL. Hence, our favorite PostgreSQL tools can be used, notably psql. However, building and typing the full connection chain to a Redshift cluster is a bit of a drag.
So, here's a simple script (source on Github) for the lazy ones among us. It simply requires a cluster name, a database name and a user name. You will be prompted for a password, unless you have a matching entry in your .pgpass file. As a bonus, your connection will be SSL-enabled. Ain't life grand?