I do the NYT puzzle on the Seattle Times website, the Universal Crossword on The Globe & Mail, and the iWin crossword puzzle. All a slightly different interface. The NYT I do in competition with myself (12 minutes is my best Sunday so far), the iWin I’m competing with other registered users for score.
Universal Crossword - Globe and Mail
iWin Daily Crossword
NYT at Seattle Times
Globe and Mail seems to be down today for some reason.