From Wiki:
Trickle charging, also called float charging, means charging a battery at a similar rate as it is self-discharging, thus maintaining a full capacity battery.
So basically, yeah.
Autospeed even has an article on how to make a trickle charger out of spare parts you might have lying around the house.
I only drive my car on the weekends, but due to all the stupid alarms and gizmos in the car it drains my battery out in about 3-4 days. This means if I don't fill my car up on a Tuesday, it won't start on Saturday after I parked it up on Sunday night. I can't use a trickle charger as I live in an apartment and I don't have mains power near where I park my car. When I do drive my car, I'll drive it for around half an hour to ensure the battery is fully charged by the time I stop.
I picked up a Jumpstarter from Supercheap, that plugs into mains power to