Easy Income from House Sitting

I've been trying for a while now to make extra and sporadic income to supplement my regular paychecks. I'm not really in a position to take on something with set hours, but I can do additional one shot work, or something that I can do on my own schedule.

I live in a building that contains about 60 units. We have a community message board that people are often advertising different events or services on. I decided to put up a note that I would be able to do some loft sitting... checking mail, feeding cats, watering plants etc. I had a bunch of people pull off the tabs with my number and email address, and a couple of weeks ago I got an email from someone who is traveling a lot right now and wants someone to keep an eye on things for them.
I'm charging a monthly fee to check their mail, make sure nothing in the loft is leaking, and fax them their rent bill.
Because they are in the same building as me, the impact on my daily life is minimal. I will be able to check in on things for them whenever I have a few spare minutes. It's the perfect little side job.

Is this something that you could do in your building or your neighborhood? Why not print up a flyer or two and see if you can provide this service to someone who lives near you!

What other low impact ways do you make extra money?