My favorite new keyboard app? Check out the free Go Keyboard app available on the Market, it lets you do a lot of customizations including changing sound/vibration of your keyboard plus a ton of free themes to use.
When you use GO Keyboard, you can change the vibration and sound settings. Set sound to “Samsung” and vibration levels to as low as you can get without losing vibration. This is pretty much what the Galaxy S2 keyboard is like and now you can use it too.
Also, another great feature about the GO Keyboard app is that it supports multiple language. I, f