just showed me a case where the jQuery tablesorter (client-side table sort) is sorting in a strange way. On first click of a table column (desc), it had positive numbers, then nulls/undefined, then negative. This could be (arguably) the correct way to sort these values.
More alarming was that clicking on the column header again did not result in toggling the sort for that column (to asc)! I'd like to track this issue as the primary bug, and look into the sorting algorithm as a secondary issue while I'm in the neighborhood.