Full disclosure: Lona's my player association leader in Star Wars Galaxies. She runs Holowood Galactic Studios. ICly, it's a collection of entertainers from The Core and a oddball crew of support staff including studio pilot Captain Mandash Grim. That's me! OOCly, HGS runs and promotes events for player associations all over the Starsider server. Sometimes they coincide with real world events or holidays. Sometimes they commemorate an important day for a group. Once in a while they're just an excuse for a good time.
HGS makes use of SWG's Storyteller tool which allows them to place objects and NPCs out in the open game world and they can creatively decorate the interiors of player stuctures as well. The Entertainer class, obviously, plays a big part in making events work and often we see highly orchestrated musical acts with dancers and special effects. Some of us, I'm looking at you Sakky, sadistically make their erstwhile friends craft and pack cases full of fireworks for hours so we can put on a good aerial show as well.
Events can include PvP contests, beast fighting arenas, gambling with dice (or with dice rolls representing cards), drawings, races and can happen planetside or in space. We even see the odd event featuring SWG's collectable card game as well especially when some new element is introduced.
All of this takes planning, coordination and logistics. Even if you're not a SWG roleplayer you'd do well to peruse Lona's Dummies series to pick up ideas for how to handle these undertakings in any game.
This includes a basic overview of how to plan and execute an event and links to many more specific guides to different styles of event from camping trips to cantina crawls to holiday festivities to PvP scenarios and information from Lona as well as other successful SWG event planners.