I usually don't keep my todo list in iCal. It just doesn't quite work for me. Stickies are much better for me. But they are not synchronized. The alternative the stickies for me is to just keep the list as a text file on one of the Linux or FreeBSD boxes, but those tend to "get lost". So what I do is maintain the list in a sticky or three and then "sync" those once in a while with a text file... No, it doesn't work very well.
It would be so very nice if the stickies could be automatically synced between systems... Maybe some day.