New Opening off of e4

I need a new opening. I have been getting too many games as black with the Ruy Lopez and the Guico Piano it is getting boring. Does anyone know a good retalliation as black other than e5 (off of e4)

Hopefully without too much theory to learn 

I like the Pirc.

I'm a huge Latvian fan if you want to play aggressively.

I also play the Caro-Kann.  I almost exclusively used it before I found the Latvian Gambit.  It's a very simple and intuitive opening in my opinion. 

I'll occasionally play the Scandinavian Defense because the positions will become so interesting.  I usually play Nf6 instead of Qxd5 though.

Sicilian is what you will hear from most players, and probably for a good reason.

You have b4 if you want to really throw your opponents out of the book and get different games.

The pirc defense if you like hypermodern theory.

The french although you have to be prepared for the advanced variation which bugs many tactical french players.  But great if you like closed positions.

If you are interested in trying a new e5 line there's always the Russian game or something.