Differences among sarcastic, sardonic and ironic

[Juzwannabebetter]

I kind of know their meanings, but I don't understand the differences among them. Can anyone give me the definitions and some examples. Thanks!!

[Cerberus™]

There are many places on the internet where this has been discussed, since many native speakers find the difference equally hard to remember, if that is any consolation. Example:
http://www.blurtit.com/q533209.html