I mentioned Eureka being picked up for a third season (Yay!) and he says of course it was, they wouldn't end a show with the ending they've set up in the episode no one has seen yet.
I'll let that little bit of bizarre prognostication on the side for a moment, and move on.
I pointed out that there are PLENTY of shows that have ended in such a way that's either a cliffhanger, or leaves fans wanting more...heck, fans generally want more and always think their show has been cancelled before it's time, even if it's run for ten years. ;) Usually because shows don't get picked up for a second season until after they've already made a finale for the season, and don't know what's going to happen, so try to make something attention grabbing to get folks watching.
"Scifi Channel never does that!"
Scifi Channel practically INVENTED it! They had a reputation for cancelling good stuff before FOX did! =)
Farscape being the #1 example that springs to mind.