Here are some sample scripts in different categories for you to practice with. Use the controls on each PDF file to advance to the next page, or right click to download and print out.
For longer scripts, try your hand at teleprompting with http://easyprompter.com. Just remember that teleprompting is not an alternative to memorizing the script most of the time! Usually only longer narrator/spokesperson scripts are earprompted or teleprompted. It's a good skill to have, but keep in mind that 90% of your bookings (and auditions) will need to be memorized!