I got the Fridge magnet idea from visiting homes of customers and members of my family who happen to have fridge magnets from traveling or visits to places as some people like collecting them.
As a result of this I thought what an ideal opportunity for promotion as I figure lots of people like to have a calendar of some sort around the house, so why not a fridge magnet! After all people are always going to the fridge or need to check the calendar for a date so every time this happens they're gonna see my advert and are more likely to give me a call first when their garden gets out of control.
I believe it's known as TOMA (top of mind awareness) here's what Wikipedia
say about it. If you see a brand or advert enough times your subconscious stores the information even if you are not looking for that product or service at the time you are somehow familiar when you do require it.
This is another reason why I went for a 12 month advert in the local community magazines; as people read the magazine they will see the adverts and if you are there month in and month out people are more likely to see and remember it more than the advert that appears once....
As for Christmas cards it is method of thanking the customer either for their business for the past year or raising the awareness of those who didn't give you the job this season.
I also sent them out before December as you're like to be the first Christmas card they get this year and won't get lost amongst all the other ones that land on the doormat for Christmas in December here in the UK or thanksgiving as you have in the States.
I designed and ordered the cards and fridge magnets from Vistaprint as they are offering some good deals on cards and magnets at the moment; anyway, I'll let you know how it goes...