According to RotoWorld, the A's have signed 3B Renato Nunez, LHP Anderson Mata and LHP Jose Torres.
Per the blurb on the sidebar, "All three are international free agents out of Venezuela. As mentioned earlier, Nunez is getting a $2.2 million bonus that will be one of the highest given to a 16-year-old this year. Fanhouse's Frankie Pillere ranked Nunez second and Mata 10th among Venezuelan prospects available this summer."

Anyone with more detailed info on any of these players can chime in!