Launch ccsm

Assign regular actions to corners by editing it's bindings. For example to show and pick from all windows of a current workspace:

To assign custom action to corner search for the 'commands' plugin.
Enable it. In the options for that plugin, you get several lines
where you can enter commands, and then in the 'edge bindings' tab,
you can set hot corners that will run that command.

For instance, you want to launch Firefox by pointing in the top right
corner. Enter 'firefox' in 'Command line x', then in 'edge bindings',
click on the button marked 'none' for that command, and enable the
relevant corner.

NOTE: 'Button bindings' is also useful, giving you the option to run the
command by going to a corner and clicking with the mouse.