Short history of Emoji characters:
Many smartphone manufacturers released Emoji first only for Japanese products as a keyboard layout. Later they became popular elsewhere as a nicer replacement for the traditional :-) or :) smileys.
Now, for some reason, first people started pushing these apps for activating Emoji on iPhones, as the layout was hidden in other markets than Japanese. Some even made a good deal of money out of it, offering activators for $0.99. Soon after, Apple started removing these apps from App Store and made the keyboard available in all countries.
Now, with OSX Lion and iOS 5, the available character set has been expanded quite a bit – hence a new avalanche of ‘activator’ apps, only this time they don’t activate anything. Basically, you have an app which copies the wanted character to pasteboard, from where you can paste it to your message. Of course the old rule applies, not the one selling is crazy, but the one who buys…
People, before paying for such a thing, please take a look at wikipedia. The Emoji page there contains all the characters you want, all you need to do is copy and paste them to a note or email them to yourself onto your iPhone.
You might want to paste them to your notes in Mail for synchronizing, just select “Paste and Match Style” from the Edit menu.