Does your Dad have a Website or could you make one for him? If you could get a few clients, starting with your Dad and maybe some of his larger customers' businesses you might be able to set up a Wesite development company?
Some people have eBay businesses. I'm retired and thinking of trying that; buying things and reselling them on eBay. Maybe your Dad has some product he needs or makes you could sell online/eBay? "Kits" of some sort? I'm a customer and now "friends" with this guy:
http://www.ezdesk2go.com/
He's a police officer and trying to start his business on the side.
Read the Classified and Job Posting forum below; there's a couple ideas in there that might work for you?