BusyCal ships new release with fruux integration.
This new version now has native fruux support, which makes it even easier to setup syncing. All you need is a username and password, and you're off!
BusyCal is one of the most feature-complete and sophisticated apps you can find for calendaring. If you feel that iCal isn't quite the power-tool you need, BusyCal is pretty much the way to go for Mac users.
Todo's are built into the calendar app, it's notification system is vastly superior to iCal's (now it has integrated into Notification Center), and calendar organization rocks too.