In addition to all these ideas (forgive if I repeated one if I misread)
- Speeder races (a la Episode 1 but of course without annoying young Anakin)
- Space races / battle (without rails)
- Much more difficult space PvE (Without rails)
- PvP 'quests'. For example if you are a bounty hunter you receive a bounty on 'x' player on the server. You have a limited time for this bounty. You must defeat them in a 1v1 situation and get a reward if you complete it, but if you lose the person with the bounty on his/her head can turn their victory in for an even greater reward? Although care must be put into implementation. Level 50 cannot collect on <lvl50 's, must be in a similar grade of gear, and possibly certain spec'd classes cannot verse others.
- Buy accessories for your armor. They don't do anything, just for aesthetics. This can greatly increase the customization of people's gear. A Jedi can look like obi wan in his trooper gear like in the clone wars cartoon and all by without buying something that sort of looks like the trooper armor, spend the money to strip the mods, then input their own.