We've shown you plenty of doorbells before, but here's ReBell, the first one with a USB port that lets you load up whatever 30-second sound effect you'd like to be summoned by. Of course, if you follow the example of this video and load up Darth Vader's entrance music, you'll never get laid again, but the choice is yours. After you've selected your fave sound and transferred it into the ReBell, connect the silver horn-like device to your existing doorbell chime, and whenever someone pushes your existing doorbell button, the MP3 or WAV file of your choice begins playing.
Since it uses two AA batteries, if you have lots of guests or like to ring your doorbell a lot, you might want to have that ladder handy for replacing the batteries on a regular basis. It lets you choose three volume levels, and there's a hook on the back that lets you remove the unit to change out the sound files or batteries. Too bad it doesn't use the power from the low voltage circuit that runs your doorbell chime. This customizable doorbell idea better be important to you, because the thing costs $100. [Think Geek]