Subbie Tasks could be, quite literally, anything they consent to.
A subbie task could be anything from having her "Look up the reference to Azrael and report, in no less than three pages, single spaced, who he was and what he did" to having her fit as many clothespins on her tits as she possibly can.
However, we're far more likely to get girls that would rather do the former and guys that would rather have the girls do the latter. Remember, this isn't about how perverted you can be; it should be about how creative and imaginative a dominant can think to make use of a submissive.
Use your imagination and get cracking. I'll have somehting up on this in a couple of days. I just need to figure out what format this wioll work best and how.