If you like to read why not volunteer for some reading activities when your son is with your H? You could read to the blind, read at a nursing home or something like that. Volunteering is AMAZING!
Or why not write and self publish a book. Create a blog/facebook/twitter to promote your book and see where you can take it. It could be a short book (I am not talking a 500 page novel here). It's not expensive to do and it would fit in your hobby of reading/being on the computer.
