There are some apps like the NBA's GameTime that let you watch certain channels or events live, but this site will let you watch a large selection of channels from the US, UK, France, Germany and Italy—for free. Crazy, awesome, and absolutely soon-to-be-sued-into-the-ground.
There are comments as recently as a few hours ago saying that the service is still working, but we weren't able to get it to load channels on our network. It seems to just be a traffic/bandwidth issue right now, but who knows how long it'll be until the lawyers and their lawyer rules show up. Enjoy it while it lasts, if it's still lasting at all. [9to5 forums]
Update: Commenters are reporting back that the service is up and working just fine for them—and that it also works on non-iOS devices.