Be sure to check out the Universal Studios web site. You can get a free kids tickets when purchasing an adult 5 day ticket at 119 US.
Here's a copy of what it says:
KIDS FREE Offer - Universal Orlando Bonus Pass
LIMITED TIME OFFER: Buy one (1) regularly priced Bonus Pass (at $119.50) and receive one (1) FREE Bonus Pass valid for Kids (Ages 3-9)!
Enjoy five consecutive days of park-to-park admission (including first day of use) to Universal Studios®, Islands of Adventure and CityWalk®!
Please note: Only the amount of regularly priced tickets should be entered when making your purchase. You will automatically receive the equal amount of free Kids tickets as the amount of full-priced tickets. Example: If you enter a quantity of 2 for the full-priced tickets, you will receive 2 free Kids tickets as well, giving you a total of 4 Bonus Passes.
Restrictions: Free ticket(s) is only valid for Kids ages 3-9. First day of admission must be used by February 10, 2005.
This ticket offer is available via Electronic Will-Call only.
All Guests $119.50
Complete Details
Universal Orlando Bonus Pass
Enjoy five consecutive days of park-to-park admission (including first day of use) to Universal Studios®, Islands of Adventure and CityWalk®!
Available Exclusively Online! Enjoy 5 Days of fun for the price of 2. Save more than $150 compared to five single-day tickets.