Nice mod!
One issue found and fixed, figured I'd pass it along so you can update the php file. After trying out the 'Only Include Subscribed Forums' function, I received a database error email advising me that 'subscribeforum' was not a valid table. Naturally this is true, because I use the vb_ prefix in my database. So I changed line 80 in the php file to include the table_prefix, and it works fine now.
In spy.php change line 80 from:
Code:
FROM subscribeforum
To:
Code:
FROM " . TABLE_PREFIX . "subscribeforum