Google "inverse square law photography" and "flash guide number" for good reading material.
You can bounce light off almost any surface. Aspects of the surface such as distance and angle to the flash, texture, color, and material all can affect the light. Only practice and experience is going to teach you to estimate the effects of different ceilings. Digital makes practicing and test shots easy. With film I quickly realized the value of a good flash meter.
In a home or building with ceilings less than 12' tall with fairly light tone, and not much texture, I figure light fall off from the distance of the path the light is taking (to the ceiling and then to the subject), and assume the surface is going to reduce flash power at least a stop. More texture or darker toned surfaces will suck up even more light.
The color of the surface is going to change the color of the light reflecting off of it. That's easy to solve with digital. With film I shot mostly BW.
Ceilings are the typical bounce surface, but you can bounce off whatever you can aim your flash at. Aim it at the white wall behind you. Bounce it off a reflector held by an assistant. Use your imagination.
For weddings I carry a Lightsphere, an Omnibounce, and a mini softbox (5"x8"). I had a Lumi-quest all in one bounce diffuser thingee kit, but I lost it. They all do a good job, and sometimes one works better than another for something I'm trying. I bought a Canon 580 flash, and I thought the little pull out white card reflector was a joke. When I actually tried it I really liked it a lot for many bounce flash situations.
I'm all for the DIY version of this stuff. Flash modifiers are expensive, but almost anyone should be able to make their own. I'm using plain old white index cards rubber banded to my flashes for bounce flash.

It's even better than the pull out 580 reflector, because I can make it bigger.