RickRoller is a novelty application. It is a repository for all things that are Rick Astley.
With this application you can do the following:
View the famous Never Gonna Give You Up video by Rick Astley on YouTube.
Purchase Rick Astley songs from iTunes.
View the official Rick Asltey website.
View the wikipedia entry for RickRolling.
Send an email directly to your friends with the RickRolling link already included. BAM! Rickrolled again!
This application uses a fair-use 10% clip of the Never Gonna Give You Up song.