Diablo III in open beta this weekend
All you need to do is log in or create a Battle.net account, create a Battle.tag and download the client. And then, when the time comes, stress test the hell out of Diablo III.
English, French, and German versions for both Windows and Mac will be available for all regions besides Korea. To address the latter issue, Blizzard said that they will be "conducting a separate, invitation-only closed beta test that will give players in Korea a chance to try out the game, along with players in the regions of Taiwan, Hong Kong, and Macau", beginning the week of April 23rd.