I think the 20 is there to stop people messing about and posting ridiculously large polls. I've seen some with well over 100 before (not at these boards), asking what your favourite ASCII symbol is xD
Besides, with polls that large, the results are virtually meaningless because you're never going to get enough votes such that it makes sense, there aren't usully that many people who'll vote in the first place
As far as I can see, I can't see any option to allow a user/non-mod or admin to edit their own poll, it seems to be a mod function only - but I'm still new to VB so might have missed something
