Disclaimer: I'm not a delta pilot.

There are a lot of nuisances involved in tipping, just wondering what everyone's take is:

Should van drivers get a tip if they don't touch your bag? Do you tip the maid? The front desk clerk? What about hotels that charge $30 for parking the rental car, do you tip the person who brings the car around? The omelette cook at breakfast? The clean up lady hovering around the buffet?