My 7 year old loves Highlights Magazine, but it is a little too much for my 4 year old.  Then I found out about Highlights Hidden Pictures Playground.  What a great magazine!  Tons of the classic hidden pictures from Highlights for kids, but this magazine has the coolest new feature: Hidden Pictures with Stickers!!  My kids love stickers and this magazine typically has three large two page hidden pictures sections with stickers to stick on the hidden items.  Then when they finish with the stickers, they can color in the rest of the scene.  This is my 4 year old's favorite activity now and she looks forward to them arriving in the mail!  And she has to hide them from her 7 year old sibling since it has wide appeal!  Check it out at Highlights' website. Great stuff!

And look here if you just want to play regular Hidden Pictures (printable or online).