After losing our faith in quick home remedies by seeing the Do-It-Yourself HD Projector Kit (You want me to make what?!), we have regained a glimmer of hope for humanity with this tip from Lifehacker for amplifying your cell phone's speakerphone...
Now this might not be any decent use to you if you're the type to only use your speakerphone feature in the car. But for those of us who live away from our immediate family and have long-distance relationships should head to the kitchen and grab the nearest (clean!) cereal bowl.
Pop your cell inside the bowl (See why it needed to be clean?), aiming the speaker down, and you should see a big difference in the sound volume. No more asking grandma to speak up.
Aiming the speaker at the bottom of the bowl reflects the sounds up the sides and out with a significantly greater "punch" than without. Likewise, the microphone seems to pick up our voices much more effectively, as well.
We realize that with an amplification technique like this one, you're likely to lose some sound quality. But it is a quick and kinda free household fix for a common problem.