From 25C3 Public Wiki
The Angel System will be used to centrally coordinate shifts and Chaos Angels. If you want to register as an angel, you need to create an account for yourself.
To find available shifts, click "available shifts" on the left hand side, then select the area in which you would like to help out, and then use the date links above the shift table to jump to the individual days. Note the "available shifts" page also contains a "show everything at once" link which shows all areas for a given day. Under "my shifts" you can also cancel your shifts up to 3h before they start.
The Angel System (Engelsystem) is now online at https://engel.congress.ccc.de/!