pgcli plugin for the Heroku Toolbelt.
Install with heroku plugins:install git@github.com:chrisanderton/heroku-pg-pgcli.git
Run from within the Heroku app directory with heroku pg:pgcli (defaults to automatic login using the Heroku DATABASE_URL for the current app).
Optionally run with a specific database URL heroku pg:pgcli postgres://*
Needs pgcli to be available in the PATH.