for commercial lines - Consulting. I analyze their website, discuss their marketing and talk about how to grow etc... Especially in the days of social media marketing. Mapping out a course of action to grow their business resonates.
Plus, in order to do a good job for them, you need to know as much as you can about their business anyway. I have the advantage of having the background to make that a natural for me, so that's helpful.
For personal lines, I probably need to think about how to offer more, because besides a holiday gift and birthday email/call I don't do much, and probably can do much more if I think about it. Will look to see what others post about their PL clients for ideas