Please does anyone know any app that I can use to to send emoticons to non-iPhone devices. All the ones I have seen are for iPhone to iPhone
Emoji, as the iOS emoticons are called, are Unicode characters that need a certain set of glyphs to be able to be displayed—think of it as a missing font not displaying correctly. If the device doesn't have the "font", it can't show it.
What you're asking for is impossible: you can't do that without a custom font installed on both devices, and on most smartphones that's not possible to do.
However, if the person on the intended receiving end is using a Mac running OS 10.7, they will display, as Apple decided to make them available in Lion.
You are asking this the wrong way around. It's down to the receiving phone to be able to understand the character codes used to send such images, and that is beyond the control of any iOS app.
Going from memory here, so may be wrong, but I believe that WhatsApp rasterises iOS emoji icons so that they can be shown on Android and Blackberry devices.