Following this answer I have created a custom service that executes a shell script that looks like this:
open -a FireFox "http://dict.cc/$1"
It works fine when I click. Then I defined a custom shortcut for it, (⇧ ⌘ L), and when I use that, the script seems to get executed twice (two tabs open, both showing the desired page). How can I fix that?
Edit: This only seems to happen when I invoce the service using the shortcut from within FireFox.
Edit 2: This gets weirder and weirder. I now created a second script for looking up stuff in Google, and bound it to the hotkey ⇧ ⌘ T. Now when I press that, it actually opens both my custom services. I have no idea why this happens.
Also, I removed both the hotkeys temporarily to check if they were used, but nothing happened when I pressed them.