http://magic.bluebones.net/proxies/ has some small improvements.
A. You can now use numbers before the card name to get multiple proxies instead of having to enter the same name multiple times.
1 Ancestral Recall
1 Yawgmoth's Will
3 Tezzeret the Seeker
etc.
Doing it the old way will still work.
B. Instead of completely ignoring entries it doesn't recognize it now reports them in a list at the end of the proxies. It will still ignore blank lines or lines that start with '#' or '//'.
Enjoy.