Yeah you might want to get a 200 amp becuse ever time you turn something on its drawing to much power.Thou i dont see this as something you would need to do i have no idea if this hurt anything leaving like it is.But the second you are running to much it you could blow a fuse.

Go to 200 amp service may help - only because in doing that work, the real cause will be fixed. Are you really drawing that much power at one time? Try to determine what is on when this happens.

Is it only one appliance that causes this?

If an electrician doesn't answer on this board, you may want to call one in to look at it. Do the load analysis first, but it sounds more like something is out of phase. I'm not an electrician, but this sounds like other problems I've read about on these and other forums. The power is in two phases. Usually one side of the breaker panel is one phase, the other side is the other phase. You've got too much on one side.

I had a simliar issue with my house and I already have 200 Amp service!

Everytime the AC would kick in all the lights in the house would dim. I found out that the transformers the power company had down the street were like 40 years old and in definate need of replacing. Others on my block on a different transformer found this same issue was corrected when theirs blew up one night and the power company replaced the transformer.

As others have said it may or may not be you.

You may have a neutral problem.

If the A/C is doing it you may have a voltage drop problem or they A/C may have to be checked.
If its happening when the refrigerator comes online then you may want to look into balancing the loads.
Also you might want to check to see how many other circuits may be on the same circuit when this load comes on.
The first place to start is to call the power company and have them check if all incoming conductors are in good shape this includes their connections especially.

Im saying you have a loose neutral!!! You should get it checked before it devours all the nice 120v equipment you have.... like computers.

You could narrow it down by determining if it is ALL lights in the house that get dimmer/brighter, or only those on a particular circuit (or circuits).
Also, pay attention to which appliances make it happen. Is it ALL major appliances or only certain ones? Are they on the same breaker?

If ALL lights and ALL major appliances in your house experience the problem, then it's probably the power company's area of responsiblity. Otherwise, you'll have to look further in your house.

If it's all on one circuit, then check every outlet and connector box on that circuit for tight connections, especially neutral.
A remote possibility is that the breaker for that circuit could be bad.