I would have to say YouTube. Very educational and free! Again, you can learn anything! I personally like to learn recipes, crafts, and organizing/cleaning.
About organizing/cleaning, for example, I was taught by a woman named ClutterBug on YouTube to do 5-minute tidy-ups instead of working too hard and attempting to do everything at once.
Then, I learned how to make the cheapest and fastest iced coffee by Sweet Charity.
Also, I learned a new hobby of making scrap fabric wreaths, which some call rag wreaths, by Simple Simon.