Create an Alphabet Song
Bash (+coreutils), 81, 87, 82, 78 bytes
Uses the man page for X, as the source of words.
Golfed
man xyst\  x|&amp;grep -Po '\b[a-z]{4,} '|sed 's/\(.\)/\u\1 is for &amp;/'|sort -uk1,1

EDITS

Used a non-existing 'xyst' man page + |&amp; to save 5 bytes;
Saved 4 more bytes, by swapping sed and sort.

Test
%man xyst\  x|&amp;grep -Po '\b[a-z]{4,} '|sed 's/\(.\)/\u\1 is for &amp;/'|sort -uk1,1

A is for also 
B is for build 
C is for computing 
D is for distribution 
E is for entry 
F is for following 
G is for graphics 
H is for hierarchical 
I is for implementations 
J is for just 
K is for keyboard 
L is for listing 
M is for manual 
N is for network 
O is for output 
P is for programs 
Q is for quite 
R is for runs 
S is for system 
T is for transparent 
U is for used 
V is for various 
W is for window 
X is for xyst 
Y is for your 
Z is for zeros