Best plugin of minecraft?

"World Edit" allows you to use a nice wand item to edit a ton of land with one cmd - So helpful!
"Essentials" adds a bunch of cmds for players and admins like pm's, fly, and invisible cmds
"Set Homes" allows you to set home TPs with cmds.
"Dynmap" allows your user to look at a web based map you generated.

I typically use bukkit.org to get my plugins and find new ones.