letters and numbers mixed

i was just thinking lately about how some people combine letter and numbers as they write -- usually on handheld devices like a blackberry -- because of a limit of space for each message.

some of them are l8r for later, 2 to represent to or too, and 4 to represent for.

here's some that i came up with:
*
1irst or f1rst
*
2econd
*
th3rd
*
4ourth
*
5i5th
*
6ixth
*
7eventh or se7enth
*
8ghth
*
n9nth
*
out of them, th3rd works best.