I just did my duty a couple weeks ago here in Toronto...
And just to clear things up, the court system will only pay you:
$40/day (IIRC) ONLY if the case lasts longer than 10 days, not including weekends and holidays
$100/day ONLY if the case lasts longer than 50 days, not including weekends and holidays.
I never got called for a case, and was only there Wednesday - Friday. It really wasn't that bad, if you go prepared. This was my second time serving, so I learned the first go round.
Bring a good book/magazine, iPod loaded with tv shows/movies, Nintendo DS or PSP, or a Laptop and you're all set.