E-books

"Mee Genius" is an app my DD likes. It comes with 5 or so free books, then has a lot to pick from to purchase. (And you can preview the books before committing to buying them...)

My DD also LOVES "Leo's Pad" it has interactive webisodes that are pretty much like watching a show, but the kids have to solve problems to continue the story. It works on things like patterns, following directions, sequencing, taking turns, descriptions, etc. I like that it lets you set up a user icon for individual children, and it tracks their progress and gives you feedback, while adjusting the level of difficulty to the kid's current level.

Another good FREE one is from Baby Bus, called "baby creative tangram" Don't let the "baby" part fool you... It's good for older kids too. It gives the kid a selection of shapes, and they can use these shapes to either match the shape given, or go in free play mode and make their own scenes with the shapes. GREAT for creative thinking!

I love that there are so many educational age-appropriate apps for young kids... I'm not huge on giving her screen time, but it definitely comes in handy on long drives, waiting rooms, or giving Mommy some time to get homework (or chores) done when Kiddo is in a "needy" mood and won't play in her room! If she's going to be looking at a screen, I prefer that she learns something from it. :)

We use the Reading Rainbow app. It's a bit pricey, but we've found it worth the money in the year we've had it. We use it almost exclusively for car and plane rides, just make sure to download the books before you get out of WiFi range.

They could play educational games if you have wifi. Like spellingcity.com, coming soon grammarcity.com, watch educational videos & take quizzes on brainpop.com & brainpopjr(all have free lite apps), you all can cook together & use the allrecipes app. Its not educational but my middle DD & I like to play chuzzle app(free version). Kindertown: various educational & fun games based on age & subject(shows you paid for or free apps to get), stack the states lite, School A to Z (educational based on subject), Playgrounds(shows playgrounds; type in zipcode). We like the jeopardy & wheel of fortune apps too :)
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My MIL bought our daughters each a kindle about 3 years ago - they were 9 and 12. I was lukewarm on the idea. They enjoyed them for a couple months but have since stopped using them completely. They have gone back to traditional books. However, my now 15 YO does read books on her phone when she's without a book. Now, part of this might be that they didn't buy any new books and had exhausted the free selections, but honestly I know so little about the kindle that I certainly didn't encourage them to use the it and they see me reading traditional books. Personally we waited as long as possible with the electronics. Oldest child got a phone when she was 14; younger one got it at 11. Oldest got a computer at age 13. We got a Wii (again purchased by MIL, is there a pattern here?) when the oldest was 10. I will say that now that the girls each have a phone I have to supervise them because they will use it constantly.

I loved the estoria app from Scholastic Books. You can download for free and get 5 books to sample. Many of the books have questions to check for comprehension also, if they can't read a work they click on it and it pronounces for them. It has helped my daughter read on her own more. And if your kids are in school, you can link the purchases to the teacher and they get the same credit as buying the scholastic books. I like knowing the 'reading level' of the book is appropriate for her and in line where she's currently at (not too hard but not too easy).

My boys like all of the Dr. Seuss e-books.

I know that there is a real book with Grover "Monster at the End of This Book" (we have it). I don't have any suggestions for the books, but I do know that they don't recommend kids having too much screen time (You could ask your pediatrician), depending on how much other screen time the kids have...but it does sound intriguing!