Rotation Codes

A rotation code replaces one letter with another by sliding the alphabet a prescribed number of spaces to the right. For instance, a rotation of 1 means that A becomes B, B becomes C, etc. You can rotate the alphabet up to 25 places. In that rotation, A becomes Z. Here is a phrase written in ROT-5:

FSSF NX MJWJ.

Can you tell what the phrase is? It's ANNA IS HERE. The ROT-13 code is unique because the letters swap two ways--that is, A becomes N and N becomes A, etc. Here is the same phrase in ROT-13:

NAAN VF URER.

Okay, so this is not a terribly inspired page. I'll try to beef it up sometime, but hopefully this will be of some use!