As far as apps, my son used the TeachMe series from ages 2 to 4 (toddler to 3rd grade).  If get one app get this series. He learned all the multiplication tables when he was 3 from dancing to songs on HaveFunTeaching channel on YouTube.  He also had some math games for practice he loved: Math Ninja and Rocket Math.

He also used as a suppliment Math board,  Math board Fractions, and some others.

I found Khan Academy to be the best teacher and assessor of true grade level but my son couldn't use it until he was 5 because it's just not as fun and engaging enough for 2 to 4 year olds.

Now my oldest just turned 6 and is starting 4th grade level on Khan next week.

Hope this helps.  I'm working on a site now I hope might help a bit too.  Just my personal exerience with my boys.

Hi!

Repeat the cards.  I'll try to be brief with my 2 cents...

Both my boys could read before 1.  My youngest (17 months old now) can read about 100 words (I honestly didn't count but it's around there) and can make phonetic sounds for all the letters and he loves it.  I can show him a word and he will do the action, I can show him a list of words and he could point out what is the correct word, I can show him an object and he could match the word to the object.  I didn't do any of these test games with him until he was about 13 or 14 months old.  When he was about 8 or 9 months he could do some of the words like when he saw "clap" he would clap or saw the word "colors" he would say "k" sound an excitedly point (indicating he wanted to see some colors).  He knows the shapes, numbers, colors, etc.

The Brill Baby Set they sell looks really good but I just learned about this site recently so I haven't tried it (maybe I'll get it in case we have a 3rd   ).  For me, all I did was:

1.) Show some flashcard games 5-20 min a day.  Too much and kids get bored, but doing nothing they forget.

1a.) For the flashcards, I repeated the first 10- 15 words almost every day, or at least every other day.  If you don't repeat they will forget, but if you only do the same 10 words everyday for 6 months it will get boring for your kid (and you ) so switch it up a little sometimes.   

2.) Show some fun Youtube videos especially phonics alphabet.  I also like to show the shapes, colors and numbers songs (I have playlists of what I used for both my boys on my LearningPlaylist youtube channel...I don't have everything I used up there yet but I'm building it SLOWLY as a hobby).  As with flashcards - too much and it gets boring, but if you never do it they forget.  I only do this at night about 45-30 min before bedtime - it helps keep him entertained while clean up as well as get the toothbrush and floss ready (I'm a dentist - you can never floss too much    ).

3.) Remember to have fun and kids only have a 5 min attention span.  If you're baby isn't in the mood for a particular activity do something else.  At a young age it has to be a fun, exciting game or they may learn to hate it.

This is what worked for me.  I welcome any feedback on ways to improve.  It looks like BrillBaby spent a lot of time coming up with good advice as well.
 

I think encouraging what the kids do know is great.  I know my neighbors only responded to their daughter in their language when she spoke English.  They didn't force her to speak (they encouraged it) but they made sure she could at least understand by only speaking to her in the language.  I wish I could, but be haven't been able to be that strict as sometimes its easier to just go back to English, but my wife tries.

I also agree with @oasis, finding a friend that speaks the language is super encouraging, especially if that friend doesn't speak English well.  It's not possible for everyone, but if you get that friend it's amazing the difference.

Before having any friends that speak the language my son didn't even try if he didn't know ALL the words to say.   

Then we found friends that come over (one near his age another a few years older) and he was super motivated to learn.  After a short while he was speaking with more vigor and confidence (with a few English words mixed in as he was learning).

Thanks for the app recommendation.  I'll check it out.

@velvetkatze, I don't know any great ones right now but I will let you know.  If you can't find a good app you may just see if you could use a good website like StarFall.com - they have some fun reading, math and spelling games as well as songs.  It's about $30 for a year subscription.   I used it with my oldest when he was 2.  I even use the simple reading parts with my 18 month old right now.  The downside (or upside however you want to look at it) is that I had to sit with him at the computer the whole time because it's not an app and I needed to help make sure he used it right with the mouse, etc.

You might keep in mind that there are not a lot of developers who bother to make apps for windows right now (PC games and programs yes, apps not so much).  Android dominates the market in terms of number of users and Apple in terms of the amount of money Apple users spend.  Windows tablets are just not dominate enough right now, so it's way down on the priority list .