I like StuffOfInterest's suggestion to provide a t= password parameter, or maybe some other means to indicate how often payouts happen. You could certainly keep the minimum at 0.001 once a day or 0.01 3x a day (I do support an increase, but I'm in the sub 0.01 a day category), but allow users to specify higher values than the minimums to reduce frequency of payout if desired, and reducing dust.

My understanding is that currently, a 2% fee is charged, but no withdrawl charge (as these are done automatically). Perhaps lowering the 2% fee a tad, and introducing a withdrawl/payout fee would encourage miners to use reduce payout frequency through whatever means choose to put in place.