Why don't you make a site for "old" people, let's say 50+.
Tell them on the site, how to use a PC and a mobile phone.
Offer then some "cheap" PC's, mobile phone's and books about it.
Give them a forum to talk about it, and don't forget your Paypal button so they can donate some money.
Believe me, if you want the money, get it from the 50+ people, they have some of it.
Give them a chatchannel too so they can talk there and meet eithother.
Post some old people shit on the forums and let them talk about it.
Offer "cheap" old people vacations where they can travel with other old people in a bus or something.
If you want to make money, you can find it there.
Make a "old" people dating site, there are some singles between them.
They want a partner, but they don't want 20 year old people to tell them on the site how horny they are. So you need profiles you can ban.

A friend of mine made a page like that 2 years ago in the Netherlands.
He is making about 1250 euro a month with it now.

Those people do donations to your site if they like it.
Make your grandfather a moderator and let him tell it his friends.

Maybe you will do something with this, maybe you won't.
It's your choise.

Good luck anyway.