Drush makes downloading multiple projects at once incredibly simple. You can download as many projects as you’d like in a single command, by simply separating each project name by a space.

Syntax
drush dl [project_1 project_2]

Example
drush dl admin_menu toolbar_admin_menu module_filter features devel views adaptivetheme corolla

The above command will download Admin Menu, Hide the Menu, Module Filter, Features, Devel, Views, the AdaptiveTheme base theme and the Corolla theme.