1. Create a new account, and do a little bit of every part of the game
Think, “Wow! I haven't done that in ages, this is great fun!”
2. Give yourself a target to save for
Maybe a status symbol, maybe a big weapon that goes “Bang!” Think up enjoyable ways to get the money!
3. Write a guide about the game
I can verify how well this works. To write a good guide, you need to go back and experience it again, which makes you look at it in a whole new light. You'll also enjoy passing on your knowledge, and perhaps the cries of thanks issuing out from the huddled masses worshipping your brilliance.
4. Start a friend playing
This one's good, because you get to show them the ropes and you can do lots of things that just aren't fun by yourself! Don't be surprised when they become better than you though, and this creates the whole opportunity of friendly rivalry. In fact, why not create a whole group of your friends?
5. Try something new
Improve something that you're bad at. It's amazing the interesting things you can discover along the way!
6. Do something completely and utterly pointless
Preferably something a lot of people will see. An example might be something I heard about a guy that created a ton of level 3 accounts on World of Warcraft, and killed them all, so the bodies spelt out a message. You don't have to be QUITE so extreme, so why not display a complete and utter disregard for wealth? You could also make a pattern out of shoes or something… in the shape of a shoe? The possibilities are endless.
7. Do something nice
Why not make a lot of something useful to new players and hand it out to them, as they join the game? You get to re-explore a facet of the game and get a warm, fuzzy feeling at the same time!
I hope you've enjoyed this little mini-guide. I like the bite sized format of this, so I might make a couple more along these lines.
Feel free to comment and make suggestions.