I cheated once; but how many songs that have the letter X as their first letter really exist?
Always Crashing In The Same Car
The Bewlay Brothers
Drive In Saturday
Everyone Says Hi
God Knows I'm Good
It's Hard To Be A Saint In The City
Joe The Lion
Pretty Pink Rose
Q is a tie: EITHER Queen Bitch OR Quicksand (I love both songs a great deal)
Running Gun Blues
S is a 3-way tie: The Secret Life of Arabia, Sons of the Silent Age or Station to Station
This Is Not America
Up The Hill Backwards
We Are The Dead
seX and the Church
The fact I could name 26 David Bowie-performed songs WITHOUT visiting a web site is evidence that I know this artist all too well. I'd strongly recommend most of these songs, too-- and given that 4 of them come from the 10 tracks on the album "Heroes", obviously that album gets very strong recommendations.
I did limit myself to songs that I either own performed by Bowie, or that I've heard him perform live.