Hexadecimal is broken
I have a problem with Hexadecimal, specifically, the choice of digits. ABCDEF after the standard arabic numerals is a poor choice, because it reverses the usual parity of the letters. A is odd, B is even, and so on, but in hexadecimal they are the opposite. So far as I'm concerned, F is 16, not 15. 0x7fff doesn't look right. My mind reads it as 0x8000.
Therefore, to alleviate this perceived inconsistency, I have selected my own set of digits. In this system, X is used to represent 10, since it's a familiar symbol for 10 from the roman numeral and it has even parity. AE represent 1115.
Decimal  0  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15 

Traditional Hexadecimal  0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F 
My Hexadecimal  0  1  2  3  4  5  6  7  8  9  X  A  B  C  D  E 
Here's some examples  I'm using 1x as the prefix here.

1xEE == 0xFF

1xX00 == 0xA00

1xE + 1x1 == 1x10

1xD + 1x1 == 1xE

1xFF // invalid  if it weren't, it would be 16
Unfortunately, I doubt many others will use this, simply because the traditional digit set for hexadecimal is so ingrained now. Furthermore, it takes some effort to unlearn it. Still, I have some hope.
This blog post was originally located at http://ajf.me/blog/archive/20120331hexadecimal.html. Today (20150725) I happened to discover this when looking through my archived old website. I'm republishing this on my new blog.