I'm not much of a car guy myself, but here are some really easy things:
Change air filters
Change oil (I use a kit that sucks it in and out through the dipstick hole, quicker and less mess)
Other easy things I have done, but usually bribe my BIL to do:
Change oil filter
Change spark plugs
Check brake pads
And yeah that's the limit of my automotive skills!
Anyone else?
