I am about to change my apartment and trying to compile a list of institutions I have to inform about my new address.
So far I have the following, please feel free to add:

Employer
Bank
Insurance company
Health Insurance
Billag
Internet/tel. provider
Strassenverkehrsamt (not sure about this one, but I have my address on the car registration)


What about the electricity provider, I get invoices from them from time to time, but do not recall having informed them about my address, maybe the landlord did it?

Anything else?

Gemeinde!

The Post! They'll forward your mail to your new address for like a year. It costs a couple francs, but I think it's worth it. Plus you'll get a packet of deals for your new address.