You can view all the Hulu "Originals" here
. (Most are not really originally made by Hulu, but simply foreign shows that haven't aired on other TV in the US.)
It doesn't really have anything to do with Roku - yes, you can watch them on the Roku, but also on your computer or any other device that Hulu Plus allows you to use.
Misfits is good, if you want a science fiction show about teenagers. I've only watched a couple seasons but plan to eventually finish it, I just haven't had time.
Pramface and Whites are both pretty funny comedies, and I've watched them both in their entirety. Pramface is about a couple of teenagers who get pregnant, and have to deal with their crazy, opposite families. Whites is about cooks working in a restaurant, who all pretty much have major character flaws.
All three are British, and they're also all very raunchy at times, so you might want to avoid them if you're a prude? Or are at work, or have kids in the room, etc.
Little Mosque is a Canadian sitcom, it's about how the Muslim people in a small town interact with the other people. If you're interested in learning about different cultures I'd highly recommend it, and if you're thinking a show about Muslims is some kind of propaganda that's going to annoy you, I'd highly recommend it because I think you need your horizons expanded. LOL.