So far:
1 5 P of I T
2 10 is 2 in B - 10 in 2 is Binary
3 X 360 - XBox 360
4 800x600 S R - 800x600 Screen Resolution
5 A B and the 40 T - Ali Baba and the 40 Thieves
6 6 Z in a M - 6 Zeroes in a Million
7 22 P on a F F - 22 Players on a Football Field
8 54 S on a R C - 54 Squares on a Rubik's Cube
9 21 D on a S D
10 4 W in a M - 4 Weeks in a Month
11 The 9 M - The 9 Muses
12 12 D of J - 12 Disciples of Jesus
13 The D to A C is A 4 L Y - The Distance to Alpha Centauri is 4 Light Years
14 122 S in a C C B - 122 Squares in a Chinese Checker Board
15 9/11 A - 9/11 Attack
16 J has 62 M - Jupiter has 62 Moons
17 4 L on a T - 4 Legs on a Table
18 2 B on a P of S - 2 Blades on a Pair of Skates
19 9 C of H in D I - 9 Circles of in Dante's Inferno
20 7 L in the W L