Guest Names:
Use these names for guests to get the following results

Simon Foster Artist Guest:
Katie Bradshaw Waving Guest
Chris Sawyer Takes Pictures
Melanie Warn Happy Guest
Tony Day Hungry Guest
John Mace Overpaying Guest
John Wardley WOW Thinking
Damon Hill or Michael Schumacher Fast Go Carts
 

Freak out the guests:
Click on a guest and leave his/her window up for a while. Then the guest will think "I have the weirdest feeling someone is watching me."

Free money:
Shut down your park for a year and you will get $10,000.

Stop Guests From Leaving:
NOTE: You can only do this if you have the Corkscrew Follies Expansion Pack. Right in front of the entrance place a "do not enter" sign and it will allow the guests to come in but not out.

Make guests stand up:
If a guest is sitting down, and for any reason or none at all, you want him to stand up, go into accessories (the button with the picture of a tree and a bench on it) and select bench. Click on the pathway that the guest is sitting on his bench on and the guest should stand up. If the guest is extremely tired, he will get up than sit down again. This wont cost you any money unless the bench or adjacent bench is broken.

Go under struts in Boat hire:
Open a new custom design boat hire. Don't add any guide tracks that the people use to steer. Have a path or ride track that uses many struts in one place but dont put it ON the water, put it one measurement (feet, meters) higher and make sure there is water underneath the path/track. If the guests move at there free will, they might go under the struts. This works best with bumper boats as the vehicle.

More money:
After you beat a level everyone in the park starts clapping for you and let go of their balloons and then they have to go buy more.

type in as guest:
Richard Tan-pic pocketer
Richard Branson-Makes everyone rich

On-Ride Photo:
On some of the rollercoasters you can add an On-Ride Photo section under special track designs. You can charge $2.00 apiece for them, and make some extra money