Method found on the BeerMoney subreddit, a site you should check out if you haven't already, as it's all about earning pocket change, or "beer money."
Get 3 or 4 cheap Android phones with at least Android 4.0 (I think 4.0 is required, do your own research if the method interests you).
Install Perk TV and let it run 24/7. Perk TV gives you points for watching ads. You can redeem the points for paypal/amazon/itunes/google play/etc gift cards, or sell the gift cards for cash. 5000 points will get you $5 and you can get that in about a week with 1 phone running the app non-stop (keep them plugged in and check them periodically as PerkTV will stop after a few hours if it thinks you're not watching anymore) 4 phones is the max the program allows, I believe, so there's an extra $20 a week for you.
This is one of the only methods I've ever heard of to make a bit of money actually doing nothing (aside from installing an app and looking at the phones occasionally). Even if you only have 1 phone to do it with, $20 a month for nothing is a lot better than $0 a month for nothing.
Not IM at all... but it's exactly what you asked for, I feel.
ETA: I don't use iOS so have no idea at all if there's a perktv for iPhone. But since Android phones are much cheaper, it's more economical to go that route