If you hate the sound of your cheap wireless doorbell (or if it's broken beyond repair), you can make it ring a real bell (or anything else you want) with an Arduino.
Not only will this manual bell-ringer sound better than a cheap doorbell, but it looks pretty cool too—especially if you use the Lego version instead of the wooden one (depending on your taste, of course):
You'll of course need a bit of electronics knowledge and soldering chops to pull it off, as with any other Arduino build. What's really neat about this hack is that since it uses an Arduino, you can make it do pretty much anything else you want at the same time as long as you have a bit of experience—like, ring a bell and notify you on your computer that someone's at the door. Hit the link to read more about the build.