If I can make one other suggestion, have the dropdown box at the top sort alphabetically by subreddit name, cablefail and cableporn should be next to each other.

alphabetical sorting added. I would be glad if you write if you have any other suggestions.

Navigation of the select box would be improved if "/r/" prefix was stripped from every item. Ex, I clicked on select box and start typing "cable" expecting for it to navigate to one of those entries, but it just hung on the first item. Alternatively, can use some fancy select component with search function, like Chosen etc.