Here's a few codes for you to try and solve (you may have to be really bored, and possibly have some knowledge of crytography :p)
Number 1:
YAOROVSEUEETHNCS
Hint: This type of code is known as a Caesar Box (Julius Caesar was the first to write codes this way.) To decipher the message, simply divide the code into four groups of four, and rearrange them vertically like this...
YAOR
OVSE
UE..
When you're done, look carefully, and a message will appear...
Number 2:
RehoatebeenoaoNstrdoSnyetkAtoahtdwud
Hint: Same as the first, but this time there are 36 letters.. so the method is slightly different.
:)