I am not going to work on this anymore so here is the source if you want to work on it.

Using two simple commands you can change from creative and survival mode. There are also some security fetchers in this plugin as well. Players can not place TNT. When a player tries to place TNT it sends the admins a message saying where they tried to place it and it automatically removes that block.

Restrictions:
- Can not drop items or open chests,dispensers,furnaces, etc, in creative
- Inventory cleared when switching to survival mode
- Players with the right permissions can see when people switch modes
- Players can not place TNT

Commands:
/creative
/survival

Permissions:
buildercontrol.* - All permissions on (Not sure if it works)
buildercontrol.use - Lets you use the commands.
buildercontrol.ignoredrop - Lets the user drop blocks in creative mode.
buildercontrol.keepitems - Keep items when switching to survival mode.
buildercontrol.spy - Lets you know when a player changes game modes.
buildercontrol.openchests - Lets you open chests and other openable things in creative.
buildercontrol.ignoreblockcheck - lets players place block (Such as TNT) while other players can not.

To do:
- add some safety things to it (no lava or fire)

This plugin was suggested by Zectric for his server.

BuilderControl