I have had my sewing machine since 2004, and it has never been serviced, and it's only been cleaned once.
I'm really worried I'm going to jinx myself here...
I've had my sewing machine since I was 12 (I turn 31 next month) and I've never had it serviced, oiled or cleaned. I do blow the dust/fabric bits out of the bobbin area though.
Sewing Gods, please don't strike me down now that I've admited it!