Re: "While you're here, could you just..."
"Should have told them to log a ticket!"
Yup.
Or logged one yourself - I'm _constantly_ on at our group about this and they think I'm being anally retentive about it but the reality is that by logging all these kinds of requests you either have something to point at when the PHBs start asking you to justify your existence or something for an edict from "on high" to be sent down telling staff to stop abusing the IT geeks' better nature.
(In the case of customers, it's also useful to show how much extra billable work you actually do as an involuntary upsell when onsite)