In case you were wondering what would qualify, I asked my social networks what were some of their pet peeves:

• Buy something: This actually is a commonly held rule for people who don’t own coffee shops. We realize that wifi is offered for free to encourage us to spend money there. So help subsidize your bandwidth.
• Don’t hog space: Even if you’re a paying customer, you’re only one paying customer. Unless your laptop and papers are buying expensichinos too, don’t spread all over a four top. Leave room for more customers to gather and subsidize your bandwidth. If you end up at a table larger than needed, offer to share it when someone else is looking for a seat.
• Don’t overstay your welcome: Like the first item on the list…only longer.
• Don’t hog bandwidth: You really don’t need to be watching Office reruns on Hulu.com. You really don’t need video chat either. Be realistic about what you need to do so the rest of the patrons don’t start taking the router’s name in vain.
• Keep it down: Use headphones so the rest of us aren’t forced to listen to your entertainment. A few “You Got Mail” notices every once in a while aren’t awful.
• Take it outside: There seems to be a gray line here concerning if you should use your cell phone. Some suggest you take the call outside. I’m in the camp that believes a cell phone conversation is the same as talking to someone at the table.
• Clean up after yourself: Don’t make the staff clean up after you.