Bukkit

You can create signs for 1vs1. The syntax is:

1. nothing
2. [1vs1]
3. command without /1vs1
4. command without /1vs1
   
   The 3. and the 4. line will be put together! There must be a whitespace at the end of the 3. line if there is another word in the 4. line and you didn't split the word. Else you needn't to write a whitespace at the end of the 3. line.
   
   Here is an example:
   
   
   
   The player who right clicks the sign will execute that command, so he will join the arena myArena.
   
   You can use the 4. line as well: