PLEASE NOTE: THESE COMMON REPLACEMENTS ARE NOT SUFFICIENT ALONE TO INCREASE PASSWORD STRENGTH.
Symbols
- @ for A
- ! for I or L
- $ for S
- % for P
- # for N
- & or + for the word and
- ~ for the word not
- ^ to indicate upper case
- | for the word or
Numbers
- 1 for I or L
- 2 for T
- 3 for E or M or W
- 4 for F
- 5 for S
- 7 for T or L or J
- 8 for B
- 0 for O
Valid symbols are not standard across websites, I would recommend sticking with these:
~!@#$%^&*()+={}[]|\<>/?
When deciding on which replacements to use, be sure to keep it simple: use a one-to-one relationship. (Do not use the same number or symbol for more than one letter and do not assign more than one number or symbol to any one letter)

February 23, 2010 at 7:59 am
[...] Replace one letter in the first word with a number (ideas can be found on the common replacements page) [...]
April 5, 2010 at 6:42 am
[...] a numeric replacement (such as those listed under common replacements) or add a [...]