My daughter received a subscription to a Tinker Crate (
http://www.kiwicrate.com/tinker) for Christmas last year. Even though the recommended age is 9-16, and she was only 8, all of the kits have been perfect for her. If you don't think your kids are quite ready for a Tinker or Doodle crate, they also sell a Kiwi Crate subscription that is geared towards 5-8 year olds.
I love this gift because she gets a new project in the mail every month, which is exactly the "more gifts throughout the year" that you wanted. We wrapped the first box up and put it under the tree, and she received another one in the mail each month after that. We are doing the same thing again this year.