I was out of town with a colleague a few years ago and we needed to participate in a call with a customer or some others on our team (I can't remember which). We didn't have a meeting room to use, so we decided to do the call from Randy's hotel room. He had eaten Pizza the night before and had an empty pizza box in his room.
When the call begain, he dialed in with his BlackBerry and turned on the speaker phone so we could both hear. After a few minutes of holding the phone, he got tired of holding it and placed the phone (with the speakerphone turned on) on the empty pizza box. As soon as he did, the sound eminating from the phone became much clearer and easier to hear. The phone we were using was an 8700c and it had a speaker port on the back of the phone. When sitting on the empty box, the speakerphone resonated with the box and amplified the sound coming from the speakerphone. What we got then was a better, clearer listening experience.
It was a great, free and easy way to enhance the speaker phone. Try it some day when you have an empty box lying around. Pizza's probably the best since it has a large enough surface area and thin enough depth that it works beautifully.