We do consulting on the side to make a living while we build our startup. What do you do when a client asks you "There's one more little thing I would like to have..."? You know that it would take you maybe 5 minutes and makes the client happy but he just keeps coming with more.<p>I don't want to know what _should I do_ but what _do you do_.
For web design, I usually do this:<p>Let's say the site design has been approved, and the buildout is underway, and the client says: "Oh yeah I want to add a blog!" I'll tell the client: "Not a problem...once the site is built out to the specifications in the original contract, we can give you a custom quote for the blog."<p>I can add a Wordpress blog in 5 minutes, and adapt the existing design into a custom theme in about 10 minutes, but the client doesn't need to know that. Putting the additional tasks in a quote with a value attached to it not only cuts down on the number of additional requests, it helps the client realize the value of your time and effort.
If it's truly a really small thing, I just do it. Otherwise, "that's outside the scope of the original estimate, we can do it for ______ on top of the original agreed amount."
When I worked in a web design agency, we offered a subscription model where clients paid a yearly or monthly rate to get, say, 2-5 hours per month of minor updates and maintenance work. It was a nice source of recurring revenue for us, and seemed to work well for our clients too.