I remember reading a few posts on the tubes months ago that JSON was going to give XML a run for its money and I thought folks were crazy. I don't see JSON totally replacing XML, but I'm definitely seeing it used in many more places where XML would have been the natural choice a couple a of years ago.
DBSlayer also intrigues me because I can see writing some pretty interesting web apps without a traditional app server. I know that DBSlayer is intended to help with scaling your DB layer, but I think it would be cool to hit it directly from the browser. There would be problems with this approach... You'd pretty much only be able to build read only apps where you don't care who sees the data... but I can see plenty of apps fitting that mold (corporate directories, stock data, sports data, etc.)