here is the delightful crack that runs from the start of the driveway, through to the back of the garage which was mostly likely caused by an earthquake some time in the last 56 years.
when we bought the house we didn't think it was that big a deal, but after some research we found out that the slab was not poured deep enough and was not reinforced by rebar so the solution to really fix it is to lift the whole garage up, dig up the whole slab and re-pour a deeper reinforced one ($cha ching$!!!)
so since that is not really an option with our budget we are going to try plan b - which involves digging out the cracked area and filling it back in with some concrete to make it smooth, then we are going to cover it with racedeck which is flexible enough to withstand the movement.
chances are this will be a temporary fix since the earth will continue to move, but we think it will make a big difference to the look of the garage. and I can stop tripping over this bit right here!