Farida, I don't imagine myself singing Habbaitak in the shower :D

I think Umm Kulthum's songs are the best for whom need to learning Arabic 

I'm just gonna say it: you have to listen to Feyrouz (Lebanese)

When you're singing in the shower, nothing beats the satisfaction of belting out "habbaitak!! habbaitak!! bissaaaayyfff!!" 

I had just posted Mashrou3 Leila's فساتين yesterday, so I'm so happy to see Ahikam recommended it!  I also really like للوطن by them (http://youtu.be/Qn3EFPOuEGM)

As for books, Syrian Colloquial Arabic by Mary Jane Liddicoat is quite good, as is FSI's Syrian Arabic Basic Course (and it's free!)

For shows, try the Lebanese web series Mamnou3 (http://youtu.be/nxEJQ4ebktQ).  It has English subtitles, and I find it really humorous as well.

If you want some songs, I know there are many great syrian singers, but I know mainly the lebanese ones (and the lebanese music is also closer to the western one). 

If you like pop - the gretest are Nancy Ajram, Haifa Wahbe and Elissa. 

If you like something less mainstream (but still popular), I like "Mashrou' Leila", this is one of their hits:

https://www.youtube.com/watch?v=6HqHdBlQEe8

There's an Israeli/Palestinian TV Series called "Arab Labor" (شغل عربي). It's partly in Palestinian Arabic and partly in Hebrew (and the DVD has English subtitles :)). Very funny!

I like music by Mira Awad, she sings in Palestinian Arabic, Fusha or English...

This song in the Palestinian dialect is very beautiful: https://www.youtube.com/watch?v=bJ5rZ08nDA0