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 (Most are not really originally made by Hulu, but simply foreign shows that haven't aired on other TV in the US.)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.