This time of year, I bake lots of holiday cookies.

OK, I'm an electrician, not a baker- but regular customers really enjoy it when you stop off for a friendly chat, and deliver some cookies. Many times, the conversation turns to "what if..", and business can develop. After all, I can actually research things I don't do that much of.
I also visit related trades I've worked with; quite often they might have something small that they'd just as soon have you do (HVAC, landscape contractors, etc.)
And, don't forget all those people who asked if you did side jobs.... never hurts to follow up. (I'm part of a two-man company; I couldn't do a 'side' job if I tried!)

This also can work if you've got new baby pics, puppy pics, etc.

Finally, this might be the time to go to a seminar, get cat-6 certified, take a course, etc.