I wanted to suggest the plugin "Found Diamonds". It is a pretty simple plugin, but I think the 2 features is offers would really benefit the server. When a user finds <block name> where block name can be set for the plugin (Diamonds, gold, iron, whatever) A chat notification apears in chat "Player name found Diamonds!" or "Player name found Gold!" The script has a timer to not repeat over a specific period of time (like 30 seconds by default) so if you find 8 blocks of gold it doesn't alert 8 times. On the servers I've seen this on it adds quite a bit to chat / show off their abilities, and obviously adds alot of extra conversation. This would also let players report possible xrayers / hacks when no mods are on, or late at night. If other players see another player finding hundreds of gold/diamond in a 1 hour time they could report it (so that staff and look at logs) which would hopefully help with catching possible cheaters.