Personally, I think I manage to do two things regularly that while they may not exactly fall into the category of kindness are, I think, examples of consideration

1) I think I am generally a considerate driver. I tend to let people out of side roads, let pedestrians cross in front of me etc. It sometimes amazes me to see the look of disbelief on their faces when a driver actually gives way to another road user or pedestrian ;)

2) If I have had particularly good service in a shop or somewhere where tipping or other gratuities are not the norm, I make a point of finding the manager and complimenting the member of staff to him or her.

Just my 2c :D

I agree with Mouse about the driving thing, we have to be considerate out there...

I also believe in helping people in parking lots who have their arms full of kids, groceries and shopping carts.