This download contains a SQL query, which can be executed against your BizTalk Message Box. The results you get are the current subscriptions in the Message Box.
Only the 'Equals Predicates' subscriptions are shown.
This script is tested on these platforms by the author. It is likely to work on other platforms as well. If you try it and find that it works on another platform, please add a note to the script discussion to let others know.