A good place to start would be Discharge, if you haven't heard them. If so, try maybe Sacrilege's first album. Newer bands to check out would be: Tragedy, Morne (slower and moodier, but they released one of my favorite albums from 2009. Definitely check them out!), Skitsystem.
It's an awesome genre with some cool bands, but as I found pretty quickly (with regards to the newer ones) a lot of it starts to just sound the same. Same chord progressions, vocal styles, etc. That's why Morne was such an awesome find.