Bukkit

To set the view distance, use the 'setview' command.

/setview 5

set my view distance to 5.

/setview server 7

set the server view distance to 7.

/setview world 4

set the current world's view distance to 4.

/setview world hell 3

set the "hell" world's view distance to 3.

/setview player admin 15

set the "admin" player's view distance to 15.

The 'resetview' command is similar, except that it does not take the view distance parameter.