Making Your iPhone's Speakerphone Louder
Here's a tip I picked up from Sean Shadmand about making your iPhone's speakerphone louder (actually, this works for any phone).
Just stick the phone on top of a cup, and the reverberation from the speakerphone in the cup dramatically increases the volume. This is especially good for iPhones, which don't have the loudest speakerphones out there (a rare case of BlackBerry envy!).