Need "sum" compatible checksum16 in Python

[Courageous]

>I think I can make a nice neat python program out
>of this mess except I need a 16 bit checksum for
>an arbitrary string such as is generated by the
>GNU utility "sum".

You've already got some responses; while this
isn't what you're looking for, I've found 16 byte
MD5s to be pretty fast, myself (I'm using them
in a project where absolute object identity is
important).

C//