LECTURE: United States presidential candidate Ralph Nader is in town. This evening, he'll be giving a lecture on the trading floor of the old Toronto Stock Exchange building, remarking on the upcoming election and discussing what's at stake for Canada. His lecture also includes a Q & A and clips from his new biographical documentary, An Unreasonable Man. Design Exchange (234 Bay Street), 7 p.m., $10. BENEFIT: The second annual ONEXONE Redken Cut-A-Thon kicks......