From: voith@soccer.sps.mot.com (Ray Voith)

Here's some of the more common chords (done with A as the root):

A  B  C# D  E  F# G# A  B  C# D
1  2  3  3  5  6  7  8  9  10 11

major [A]: 1 3 5                            A C# E
minor [Am]: 1 3b 5                          A C E
seventh [A7]: 1 3 5 7b                      A C# E G
minor seventh [Am7]: 1 3b 5 7b              A C E G
major seventh [Amaj7 or AM7]: 1 3 5 7       A C# E G#
sixth [A6]: 1 3 5 6                         A C# E F#
minor sixth [Am6]: 1 3b 5 6                 A C E F#
augmented [A+]: 1 3 5#                      A C# E#  (A C# F)
augmented 7th [A7+]: 1 3 5# 7b              A C# E# G
diminished [Adim]: 1 3b 5b                  A C Eb
diminished 7th [Adim7 or Ao]: 1 3b 5b 7bb   A C Eb Gb
                              1 3b 5b 6     A C Eb Gb
seventh (flatted fifth) A7(5b): 1 3 5b 7b   A C# Eb G
minor 7th (flatted 5th) A7(5b): 1 3b 5b 7b  A C Eb G
ninth [A9]: 1 3 5 7b 9                      A C# E G B
minor ninth [Am9]: 1 3b 5 7b 9              A C E G B
major ninth [Amaj9 or AM9]: 1 3 5 7 9       A C# E G# B
eleventh [A11]: 1 3 5 7b 9 11               A C# E G B D
diminished 9th: 1 3 5 7b 9b                 A C# E G Bb
added ninth [A(9) or A(2)]: 1 3 5 9         A C# E B (A B C# E)
added fourth [A(4) or A(11)]: 1 3 5 11      A C# E D
suspended [Asus or Asus4]: 1 4 5            A D E 
suspended 9th [Asus9 or Asus2]: 1 2 5       A B E (A E B)
7th suspended 4th [A7sus or A7sus4]: 1 4 5 7b    A D E G
7th suspended 9th [A7sus2 or A7sus9]: 1 2 5 7b   A B E G
fifth [A5 or A(no 3rd)]: 1 5                     A E
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

typically X/Y means "an X chord with a Y in the bass".
Sometimes Y is part of the X chord but not the root (e.g., C/G)
Sometimes it is not (e.g., Bb/C).

C/D is a C chord with a D bass note (xx0010).
A/B is an A chord with a B bass note (x22220).
G/D is a G with a D bass (xx0003).  And so on.