The first and easiest to implement option for shower speakers is a set of external speakers. These usually take the form of a waterproof station with speakers that can be brough into the shower with you and attached to the wall via suction cups or a mounting bracket. In some cases they may simply hang over your shower faucet with a rope.
Many styles are controlled by an iPod or other portable MP3 player. In some models, the MP3 player directly connects to the station and sits in a waterproof dock. In other models, the iPod connects to a receiver outside of the shower and wirelessly transmits the signal into the shower.
Naturally, as these are controlled by a portable MP3 player, you have full control over the playlists that you are listening to: just program it into your player and you’re done!
This kind of portable external shower speaker is usually priced very reasonably (under $100) and provides a good entry point into the world of shower speakers.