Predictit has helped me become more interested and knowledgeable about politics, and I think it's a rather fun site. I've been active in the tweet markets of the president, and vp for a while now and it can pay off pretty good if you take a disciplined approach... or just go all out lol!
They currently have a promotion which is kind of rare.
If you have any questions, post here and I'll help best I can. Have fun!