Roller Coaster Tycoon: Corkscrew Follies

Photographer guest:
Enter Chris Sawyer as a guest name.

Artist guest:
Enter Simon Foster as a guest name.

Increase guest happiness:
Enter Melanie Warn as a guest name.
You can rename the guest to another name and repeat this on another guest as needed.
Information in this section was contributed by Metman64. 

Waving guests:
Enter Katie Brayshaw as a guest name.

Hungry guest:
Enter Tony Day as a guest name.
This guest will usually be hungry or very hungry.
Information in this section was contributed by Raymanjr.

"Wow!" thinking:
Enter John Wardley as a guest name.

Guest pays double entrance fee:
Enter John Mace as a guest name.
Information in this section was contributed by Grasshopper.

Faster Go-Karts:
Enter Damon Hill as a guest name.
Enter Michael Schumacher as a guest name to race even faster.

Multiple names:
You can have more than one person with the same name (which works well when using the cheats) by changing the capitalization of various letters.
For example Chris Sawyer can be used on another person by making all letters lower or upper case (chris sawyer and CHRIS SAWYER).

Hidden initials:
In the Haunted Harbor level, choose the "Buy Land" option.
You will notice you have a lot of land to buy around the park, however go up to the very top right hand corner of the screen.
You will find that you have a few small patches of land you can buy.
Buy them and turn the camera angle the correct angle and you will notice that the land you have bought spells out "C S", which are the initials of Chris Sawyer, the man who originated Roller Coaster Tycoon.